ahfc building monitoring system project

AHFC Building Monitoring System Project Prepared for: Alaska Housing Finance Corporation

Final Report for Deliverables 2, 6 and 7:

Installation of Monitoring System,

Scope of Future Work, Use of BUDS and

ARIS

June 30, 2013

Prepared By:

Analysis North: Alan Mitchell

Arctic Energy Systems: Phil Kaluza

Under Subcontract to: Alaska Energy

Engineering

Table of Contents 1. Summary of Installed Monitoring Systems ............................................................................. 1

2. Monitoring Benefits and Important Issues by System Type ................................................... 4

2.1 Overall Building Energy Use ............................................................................................. 4

2.1.1 Monitoring Approaches ............................................................................................ 4

2.1.2 Benefits to Building Operators ................................................................................. 6

2.1.3 Benefits to Energy Managers .................................................................................... 7

2.1.4 Benefits to Designers .............................................................................................. 10

2.2 Heating Boilers ............................................................................................................... 12

2.2.1 Monitoring Approaches .......................................................................................... 12

2.2.2 Benefits to Building Operators ............................................................................... 14

2.2.3 Benefits to Energy Managers .................................................................................. 15


2.3 Space Heating Distribution ............................................................................................. 15





2.4 Domestic Hot Water System .......................................................................................... 18





2.5 Ventilation System ......................................................................................................... 21


2.5.2 Benefits to Building Operators and Energy Managers ........................................... 22


2.6 Cooling System ............................................................................................................... 23




2.7 Space Temperatures ...................................................................................................... 25



2.8 Space Lighting Levels ...................................................................................................... 26




2.9 Space Occupancy ............................................................................................................ 28





2.10 Snowmelt Systems ...................................................................................................... 29




3. Internet Access and Network Impact Issues ......................................................................... 31

4. Scope and Costs for Future Buildings ................................................................................... 33

5. Use of Smart Meters for Acquiring Data .............................................................................. 36

6. Utilization of BUDS and ARIS Projects for Data Collection and Storage ............................... 37

7. Remote Control of Systems, Task 12 .................................................................................... 37

8. Appendix: Measured Values ................................................................................................ 38

9. Appendix: Monitoring Installation Notes and Issues ........................................................... 41

9.1 Monnit Wireless Sensors ................................................................................................ 41

9.1.1 General Issues ......................................................................................................... 41

9.1.2 Temperature Sensors .............................................................................................. 42

9.1.3 Pulse Counter Sensor (last item applies to Dry Contact Sensor as well) ................ 42

9.1.4 Occupancy Sensor ................................................................................................... 43

9.1.5 Lux Light Level Sensor ............................................................................................. 43

9.1.6 Repeaters ................................................................................................................ 43

9.2 Cradlepoint Cellular Router ............................................................................................ 43

9.3 Ultrasonic Flow Meter, model TUF-2000M ................................................................... 45

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1. Summary of Installed Monitoring Systems

Building Monitoring Systems (BMS) were installed in three AHFC buildings: Chugach Manor

(1281 E 19th Ave, Anchorage), AHFC Headquarters (4300 Boniface Parkway, Anchorage), and

Glacier View (200 Lowell Canyon Road, Seward). The total sensor point counts for each

installation are: Chugach Manor = 21, AHFC Headquarters = 38, Glacier View = 23; this includes

values that are calculated from other measured values. This project monitored a wide variety

of system types within these buildings and therefore resulted in a high sensor count for each

building. For future AHFC monitoring efforts, a reduced and more selective set of sensors is

advisable to reduce cost and improve manageability of the system.

The parameters that were chosen to be monitored either affect the energy use of the building,

the comfort of the occupants, or affect HVAC maintenance tasks required in the building. A

detailed list of the sensors and pertinent information about the sensors is provided in the

Section 8. Section 9 provides installation notes, and operation/configuration issues related to

the monitoring technologies used in this project.

Figure 1 below is a diagram of the overall structure of the Building Monitoring System. The

monitoring system stores the collected data on Internet-accessible servers, and the data is

accessible to users of the data in near real-time. The core of the system is the “BMS Database

and Web Reporting Application”. This custom web application consists of a database for

storing sensor data and a web-based application for viewing charts and reports that display the

data to users. The charting/reporting application is available online at

http://bms.ahfconline.net.

The BMS database receives sensor data from three different

sources. One source of data are wireless sensors from Monnit,

Inc. (http://www.monnit.com), which are used to sense

temperatures, light levels, occupancy, and various other

parameters within the buildings. The picture to the right

shows a Monnit wireless temperature sensor with an external

probe and a “gateway” that receives the sensor transmission

and forwards the reading to an Internet server. In the Figure

1 diagram, the Monnit sensors and gateways are represented

by the pentagon in the lower right of the figure.

http://bms.ahfconline.net/

http://www.monnit.com/

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Figure 1: General Structure of the AHFC Building Monitoring System.

The Monnit gateway forwards sensor readings to the iMonnit Web Portal, which is the

database and portal maintained by Monnit Inc. to configure Monnit sensors, store sensor

readings, and view the stored data. This web portal is accessible at https://www.imonnit.com.

When new sensors are added to the monitoring system, they must be added and configured

through this web site. This web application also provides the ability to establish text message

and/or e-mail Notifications that are sent out when sensor values move outside of user-defined

ranges. Notifications can also be sent when sensor battery capacity is low or when sensors fail

to report readings at their specified reporting interval. This notification feature can be used to

warn maintenance personnel when heating or hot water temperatures fall outside of

acceptable ranges, allowing for quicker repair time or avoidance of catastrophic failures.

The iMonnit portal allows for some very simple reporting and charting of the collected sensor

data. However, the breadth of reporting and charting tools is limited, and there are no energy-

specific or building-specific reports available on the system. The Monnit system has been

developed for use in a wide variety of applications, not just building monitoring. To remedy this

https://www.imonnit.com/

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shortfall and to allow for the inclusion of data other than that collected by Monnit sensors, we

built the separate BMS Database and Web Reporting Application. To incorporate the Monnit

sensor data into the BMS Database, we used the “Push incoming data to 3rd party” feature of

the iMonnit system. That feature allows received Monnit sensor data to be forwarded to

another server on the Internet.

Weather services that have Internet-accessible data are the second source of data for the BMS

database. We built retrieval features into the BMS database that allow for acquisition of data

from the National Weather Service (NWS) data and the Weather Underground service. Using

these services eliminates the cost of installing and maintaining outdoor weather sensors. Also,

these weather sources generally have high quality data, a quality level that is difficult to achieve

at a reasonable price with site-specific sensors.

The Weather Underground service allows access to a wide variety of weather stations;

however, free access to the service is limited to 500 retrievals per day. So, we utilize data direct

from the National Weather Service where possible (no limit on free access). We did need to

utilize the Weather Underground service for the AHFC Headquarters building, since the Alaska

Science Center weather station located on the Alaska Pacific University campus is much more

appropriate than the nearest NWS site.

The third source of data is the Building Automation System controlling the HVAC system in the

AHFC Headquarters building. This is a highly sophisticated Direct Digital Control system that

communicates with many sensors throughout the building, in the boiler plant, and in the

Rooftop HVAC unit. The control system was installed with the renovation of the HVAC system

in 2012. The control system uses the Tridium Niagara AX software framework. Gordon

Timmerman of MacDonald-Miller, the controls contractor for the building, identified a 3rd party

software module that allows real-time export of data from a Niagara AX system.1 This software

module was purchased, installed and configured to export a number of sensor values from the

building automation system. Those sensor values are posted directly to the AHFC BMS

database, allowing those sensor values to be reported, charted and viewed along with the two

other sources of data feeding the BMS database.

The difficulty with extracting data from building automation systems is that the process of

exporting data in real-time will be different for each brand of system. The solution that we

discovered for the Niagara AX system was very economical ($100 for the software module,

ignoring research and system configuration time) but will not be applicable to other system

types.

1 The software module is the HTTP Poster by Kors Engineering, http://www.korsengineering.com/products/http-

poster-for-niagara-ax/.

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For purposes of adding and configuring sensors and reports for the AHFC Building Monitoring

System, a system administrator needs to interact with both the iMonnit web portal to configure

Monnit wireless sensors and notifications and interact with the BMS Database and Reporting

Application to configure sensor and report settings for that application. The administrative

interface for the BMS Database and Reporting Application is available at

http://bms.ahfconline.net/admin/ through a password-protected log in.

2. Monitoring Benefits and Important Issues by System Type

Monitoring equipment was installed for a variety of different energy-using systems. In this

section, the monitoring benefits, approaches, and issues are discussed for each type of energy-

using system addressed by this project. Benefits are separated by three types of benefit

recipients: building operator/maintenance staff, building energy managers, and building/HVAC

designers. Although only a small amount of monitoring data has been collected by the project

to date, actual collected data is used to illustrate some of the types of monitoring benefits.

2.1 Overall Building Energy Use

2.1.1 Monitoring Approaches

This category refers to monitoring the total amount of fuel and electricity used by

the building.

Chugach Manor

and AHFC

Headquarters use

natural gas as fuel.

To monitor the gas

flow, we purchased

Miners and Pisani

MVP-10 pulse

output units ($225

each) that attach to

the commercial

natural gas meters

owned by Enstar

Natural Gas on

these two buildings.

Enstar personnel

installed the pulser

units on the meters

Figure 2: AHFC Headquarters Pulse Output attachment to the Natural Gas meter (upper left) and associated wireless pulse counting sensor (upper right). The cover has been removed from the enclosure holding the wireless sensor. Flexible conduit protects the cable connecting the gas meter pulser unit to the wireless sensor.

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for a charge of $150 per meter. These pulse output units close and open a set of

electrical contacts each time 0.1 ccf of natural flows through the meter. We

connected a Monnit wireless pulse count sensor to count and transmit the total

number of pulses in each 30 minute interval. Figure 2 shows the installation at the

AHFC Headquarters building.

At the Glacier View building in

Seward, the fuel utilized for

heating is fuel oil. Fuel oil flow

meters were installed to

measure fuel flow from the oil

tank to each of the two boilers.

Because each boiler has a

dedicated and separate fuel line,

each of the two boilers needed a

separate fuel flow meter. Elster

4p fuel oil meters were used

($470 each); these meters come

with pulse output contacts that

were connected to a Monnit

Pulse Counter sensor. Figure 3

shows one of the meters

installed at Glacier View.

Building electricity use was

measured at two of the three

buildings monitored: the AHFC Headquarters

and Chugach Manor. Measuring electricity

use is more important for office buildings

than for multi-family buildings because

usage per square foot is higher and

electricity savings opportunities are

generally more abundant. For the two

buildings measured, we chose to have the

electric utility, Anchorage Municipal Light

and Power, install a pulse output unit on

their building electric meter ($1700 per

meter). We then connected a Monnit

Figure 3: Fuel Oil Meter installation at the Glacier View building. The translucent plastic box at the top of the picture is the fuel oil meter. The wireless pulse counter sensor is attached to the Unistrut at the left side of the picture.

Figure 4: Chugach Manor Electric Meter measurement system. The utility's pulse output unit is shown in the lower right. The wireless pulse count sensor is upper right.

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wireless pulse count sensor to that pulse output unit. Figure 4 shows the installation

at the Chugach Manor building.

Another option for measuring building electricity use is installation of a separate

electric power transducer that utilizes its own voltage taps and current transformers

to measure electricity use directly. The Dent Instruments PowerScout

(http://www.dentinstruments.com/power_meters_demand_response_branch_circu

it_monitoring.html) is one such product. For smaller buildings, this approach may

be less expensive than paying the electric utility for installation of a pulse output

unit on their meter. Although, the amount charged to install a pulse output device

(KYZ relay) on the electric meter can vary substantially across utilities. The charge at

Anchorage ML&P is $1700, but the charge by Golden Valley Electric in Fairbanks is

only $480.

2.1.2 Benefits to Building Operators

The benefits from overall building energy use monitoring primarily accrue to Energy

Managers and Building Designers. However, one benefit that operators can realize

from this data is the ability to determine how much boiler capacity is required to be

operational at different times of the year. For example, the total heating and

domestic hot water loads diminish during the summer such that some boilers in a

multi-boiler plant can be turned off to save energy and allow for routine

maintenance.

Figure 5 below shows the total natural gas usage at Chugach Manor, measured in

30-minute intervals during a 1.5 month summertime period. The equipment using

natural gas at the Manor includes the main boiler plant and the clothes dryers.

When looking at peak natural gas usage, the clothes dryer usage of about 30,000

Btu/hour per operating dryer is relatively small and can be ignored. This graph

shows that with the exception of one large peak in usage, natural gas usage during

the summer stays less than the high firing rate of one boiler, which is 1,703,000

Btu/hour (input). Note that Manor boilers are currently locked on their low firing

rate of approximately 750,000 Btu/hour (input). To implement a strategy where only

one boiler operates in the summer, one boiler would need to be configured so that

burning at its high firing rate is possible.

The large peak shown in the graph that exceeds the 1,703,000 Btu/hour level does

not need to be met for the following reason. During warm days, the space heating

distribution pump at the Manor is turned off by the control system. Late in the

evening after outdoor temperatures cool back down, the pump is turned back on.

Restoring distribution fluid to high temperature and serving a number of units with

http://www.dentinstruments.com/power_meters_demand_response_branch_circuit_monitoring.html

http://www.dentinstruments.com/power_meters_demand_response_branch_circuit_monitoring.html

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high thermostat settings causes a very high initial load. This load could be met more

gradually by one boiler without any significant occupant discomfort.

Figure 5: Natural Gas Usage in 30 minute Intervals at the Chugach Manor.

2.1.3 Benefits to Energy Managers

Overall building energy use measurements provide substantial data to Energy

Managers, even though the energy usage is not disaggregated by energy end use.

One use of this data is to compare energy usage across different buildings. Figure 6

below shows a sample comparison of one week’s fuel usage across the three

buildings monitored in this project. The fuel usage is normalized per square foot of

building floor area and per heating degree-day to help make the usage more

comparable across different buildings in different climates. However, expertise and

judgment is still required when interpreting these graphs. For this example

comparison, the AHFC Headquarters is an office building with little domestic hot

water usage. Particularly during a summertime period with low space heating

usage, it is not fair to compare an office building against multi-family buildings.

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Figure 6: Sample Energy Usage Comparison across Buildings.

The BMS Web application also has a graph for comparing electricity use per square

foot across monitored buildings.

The variation in energy use across hours of the day is also informative to an Energy

Manager. Figure 7 below shows how the electricity of the Chugach Manor varies

across hours in the day. It is important to note the Y-axis scale. Electricity use peaks

during the 6 – 7 pm hour at about 114 kW. The low hour is the 3 – 4 am hour when

the electricity use falls to 95 kW, only 17% less than the peak usage hour. This very

flat hourly profile points out the high energy use associated with the many 24/7

loads present at the Manor, including hallway lighting, hallway and lounge HVAC

systems, and the high 24/7 pumping power associated with the DHW system.

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Figure 7: Hourly Profile of Electricity Use at the Chugach Manor. Take note of the Y axis scale. The electricity use only varies from a low of 95 kW in the middle of the night to a high of 114 kW.

Trending of energy usage data is useful to determine if changes have occurred that

negatively affect energy use. The challenge with energy usage trending is to control

for climate and schedule variables that can affect energy usage. Figure 8 below is an

example of a graph that shows Boiler Fuel Use at Glacier View plotted against

outdoor temperature (the data for the graph came from a prior data collection

effort). Each point in the plot is one particular day of data; the X value is the average

outdoor temperature for that day and the Y value is the average fuel use of heating

plant. Clearly, the graph shows that fuel use increases when the outdoor

temperature is cold. The value of this plot is to show when the building deviates

from the normal trend, indicating an event that is causing excessive energy use or an

action that reduced energy use. The way this graph is formatted, recent days are

highlighted with special points on the graph.

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Figure 8: Glacier View Boiler Fuel Use plotted against Outdoor Temperature.

2.1.4 Benefits to Designers

Because the boiler plant in AHFC buildings generally dominates the total building

fuel usage, particularly during design conditions, overall building fuel usage data can

be used to determine the necessary size of the boiler plant. The graph in Figure 8

from the prior section can be used for detecting fuel use anomalies, but it is also

useful for determining the design energy load for the boiler system. The graph

shows that at the Seward heating design temperature conditions of 7 degrees F, the

Glacier View boiler plant uses about 370,000 Btu/hour of fuel. This value is a much

better starting point for a design load analysis than a standard heat loss calculation

approach that relies on many uncertain and unmeasured quantities.

Good information about air-conditioning sizing can also be garnered from whole-

building electricity use data. Figure 9 and Figure 10 below compare electricity usage

at the AHFC Headquarters on a very warm (outdoor temperatures peaking at 85 deg

F in the afternoon) day and a cool summer day (outdoor temperatures in the low

50s). During the warm afternoon of June 18, total building electricity usage was

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about 275 kW. During the cool morning of June 21, total building electricity usage

was 155 kW. Both days were work days and lighting and plug loads were quite

similar during these periods. The 120 kW difference between the two load values is

air conditioning usage, and is a good estimate of the peak air conditioning load of

the building, assuming the existing air conditioner had sufficient capacity to meet

the high load.

Figure 9: Electricity Use at the AHFC Headquarters on June 18, 2013, a very warm day. Peak usage reached about 275 kW.

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Figure 10: Electricity Use at the AHFC Headquarters on June 21, 2013, a cool summer day. Morning usage when no mechanical cooling was being used was about 155 kW.

2.2 Heating Boilers


A variety of boiler parameters can be monitored, including:

Boiler Outgoing Supply Temperature

Boiler Return Water Temperature

Boiler Flue Gas Temperature

Boiler On/Off Status (i.e. recording when the times when the boiler fires and

when it shuts off.)

Boiler Alarm Status

For the temperature measurements other than flue gas, we used Monnit wireless

external probe temperature sensors strapped on a pipe surface. Figure 11 below

shows how we typically mounted the temperature probe on the pipe. The white

thermal grease is important to ensure good thermal contact between the pipe and

the sensor. Pipe insulation must be reinstalled over top of the sensor to reduce the

influence of the ambient air temperature on the measurement. Measurement

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errors of multiple degrees Fahrenheit will occur if good installation procedures are

not followed.

Figure 11: Typical Mounting Configuration for a Temperature Probe on a Heating System Pipe. Two black cable ties are shown in the picture holding the sensor against the pipe. The white paste is thermal grease (heat sink compound), which ensures good thermal contact between the pipe and the sensor. The pipe insulation must be reinstalled over the temperature sensor in order to achieve accurate measurements (not shown in this picture).

We did not measure boiler flue gas temperatures in this project. However, we

provide here some suggestions on approach. For monitoring boiler flue gas

temperatures, a special high temperature sensor is needed. Monnit sells a high

temperature wireless sensor that can measure temperatures as high as 700 degrees

F. This may be adequate for many applications. If higher temperatures will be

present, a thermocouple transducer that produces a voltage or current output could

be connected to a Monnit Analog Voltage sensor or Monnit 0-20 mA sensor.

Boiler On/Off cycles can be recorded in a couple of different ways. For the Glacier

View boilers in this project, we installed a 120 VAC relay (Functional Devices RIBU1C)

across the fuel solenoid for each boiler. When the fuel solenoid is energized and

allowing fuel to flow to the boiler, our relay contacts close. A Monnit Dry Contact

sensor is connected to the relay contacts and transmits the time of the beginning

and end of the boiler firing cycle. Figure 12 shows the installation on one of the

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Glacier View boilers. Another

approach to sensing boiler

cycles is use a Current Switch

clamped onto the wire feeding

the fuel solenoid. When

current flows through the wire,

a pair of contacts is closed. The

contacts can be connected to a

Dry Contact sensor.

Some boilers have special alarm

contacts that close when the

boiler locks out or malfunctions.

The Energy Kinetics boilers used

at Glacier View have these

contacts. They were connected

to Monnit wireless Dry Contact

sensors, as shown in Figure 13.

2.2.2 Benefits to Building

Operators

Boiler monitoring can provide

useful information to building

operators. If sensors are

connected to boiler

alarm contacts, these

sensors can be

configured to notify

building operators via

text message or e-mail

when a boiler

malfunction occurs. A

temperature sensor on

the Primary Loop or

Distribution Loop can be

configured to notify an

operator when the Loop

Figure 12: Sensing Boiler On/Off Cycles using a Relay and Dry Contact Sensor. The Orange and Yellow wires are from the contact side of the Relay and connects to the Monnit Dry Contact Sensor. We are experiencing problems with electrical noise in this installation, which may be remedied by mounting the Dry Contact Sensor some distance away from the burner motor.

Figure 13: Boiler Alarm contacts (terminal block at bottom of controller) connected to a Dry Contact sensor (lower left) for sensing boiler malfunctions.

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temperature falls below an acceptable level due to a system problem. Monitoring

flue gas temperature of the boiler can indicate when a boiler tune-and-clean is

needed, as flue gas temperature will typically rise as the combustion pathway

becomes dirty. Monitoring boiler On and Off cycles can inform a building operator

whether Lead/Lag controls are set properly.


By establishing boiler failure notifications as described in the prior section, system

operators may become more comfortable with operating boiler systems without hot

standby capacity, particularly during the summer when consequences of boiler

failure are not large. For example, in section 2.1.2 we discussed the possibility of

operating only one boiler during the summer at Chugach Manor. Currently, three

boilers are hot and operating at that facility. Shutting down two boilers during the

summer will eliminate the substantial standby losses of those boilers.

Monitoring return water temperatures to condensing boilers will indicate whether

those boilers are operating under conditions that allow them to condense and

achieve high efficiency. If condensing conditions are not being achieved, lowering

system temperatures to achieve higher efficiency can be attempted.

Monitoring boiler On/Off cycles will identify efficiency-robbing short-cycling

problems. In addition, if the boiler plant operates at a fixed firing rate, On/Off cycles

can be used to estimate total fuel use of the boiler. This approach to measuring

boiler fuel use is less expensive than installing fuel flow meters, although less

accurate.


For fixed-firing-rate boilers, observing cycles during a design winter day will indicate

how much boiler capacity is being used to meet design conditions.

2.3 Space Heating Distribution


Below are parameters that can be monitored for the hydronic distribution loop that

serves the space heating needs of a building:

Outgoing Supply Fluid Temperature

Incoming Return Fluid Temperature

Flow Rate of Fluid

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Pressure Drop across Distribution System

At the Chugach Manor, we are only monitoring Supply and Return temperatures for

the two hydronic distribution loops in the building. At Glacier View, we are

monitoring Supply and Return temperatures as well as the flow rate to the

distribution loop. At the AHFC Headquarters, a number of distribution loop

parameters are available in the building automation system, but we have not

enabled recording of any of those yet.

For flow rate measurement, we are using a non-intrusive transit-time ultrasonic flow

meter. No plumbing work is required to install the ultrasonic sensors, as shown in

Figure 14 below. The flow meter used is the model TUF-2000M available for about

$250 from a number of Chinese-based sellers through E-Bay. After installing the

sensor, accuracy when attempting to measure low flow rates can be substantially

improved by “zeroing” the meter. The zeroing process involves shutting off flow in

the pipe and executing the zeroing command on the meter (Menu 42). Operating

experience with the meter has been acceptable so far.

Figure 14: Ultrasonic Flow Sensors installed on the Space Heating Distribution loop at Glacier View. Important installation details include the use of Dow Corning 111 valve lubricant and sealant as acoustical coupling between the sensor and the pipe. The pipe should be sanded and cleaned before installing the sensor.

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Text or e-mail notifications can be configured to inform building operators when the

Supply temperature to the building falls below acceptable limits. For systems with

outdoor temperature reset of the supply temperature, the notification temperature

limit may need to be changed seasonally.


Energy Managers can verify operation of the supply temperature outdoor reset

control, if one is present on the building, by observing the variation in supply

temperature with outdoor air temperature.

Pump sizing and/or VFD pump settings can be verified by examining the

temperature difference across the distribution loop under design conditions.

Hydronic systems should deliver sufficient heat with a delta-T of 15 degrees F. If the

observed delta-T is substantially less than this during design conditions, the

circulation pump is likely oversized or the controlled pressure setting on the VFD

system is excessive.

If the flow rate of the distribution system is being measured, analysis of this flow

rate during warm periods can indicate whether there are many leaky zone valves or

flow bypasses in the system. For example, even during relatively warm periods, the

distribution flow rate at the Glacierview building exceeds 30 gallons per minute.

This probably indicates the existence of some unnecessary bypass or constant flows

that are using pumping energy and radiating heat during periods when no heat is

required.


The sizing of building’s distribution pumping system can be aided greatly by

measured data. Most pumping systems are substantially oversized. At one point,

the Glacier View distribution pump was a 3 HP model. A 1 HP pump is currently

installed and will prove to be adequate. The Supply/Return delta-Ts during design

conditions can indicate whether the pump is sized properly. If flow rate is being

measured along with delta-T, as is the case for Glacier View, the design distribution

load can be determined and used in a pump sizing calculation. For Glacier View,

over 1 kW of pumping power was saved by downsizing the pump. Over a ten-year

period, over $10,000 of electricity will be saved by appropriate sizing.

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2.4 Domestic Hot Water System


Domestic Hot Water System parameters that can be valuable to monitor include:

Flow rate of cold water into system (which equals the flow rate of hot water

being used).

Temperature of cold water into system.

Outgoing Temperature of hot water to the building.

Temperature of hot water supplied to mixing valve.

Temperature of return recirculation water.

Flow rate of recirculation water.

On/Off cycles of the circulation pumps delivering heat to the indirect DHW

storage tanks.

On/Off burner cycles of a standalone DHW tank.

In the Chugach Manor, we installed an ultrasonic flow meter, similar to the one

described previously in the Space Heating Distribution section, to measure the flow

rate of incoming water. We also did a one-time measurement of the recirculation

water flow rate using a portable ultrasonic flow meter. Numerous DHW

temperatures in both the Chugach Manor and Glacier View were measured with

strap-on wireless temperature probes.

To measure On/Off cycles of a circulation pump feeding an indirect DHW tank or a

burner on a standalone tank, a relay and dry contact sensor can be used. See the

discussion of the boiler On/Off cycle measurements in section 2.2.1


Notifications can be configured to inform building operators when outgoing DHW

water temperatures are outside of an acceptable range. This will quicken repair of a

failed system and potentially avoid safety concerns with excessively hot tap water.

The measured data from this project has been very useful in the diagnosis of DHW

problems resulting from the Glacier View renovation. Figure 15 below shows three

of the DHW temperatures measured at the Glacier View facility for one day.

A number of problems are illustrated by the data. The top line shows temperatures

delivered from the DHW storage tanks to the mixing valve that tempers and

regulates the hot water going to the building. The tank water temperature is

approximately 170 degrees F, substantially in excess of the needed 120 degree F

target delivered temperature. These high tank temperatures reduce the efficiency

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of the boiler supplying the tanks and increase the risk of scalding should the mixing

valve malfunction.

The middle line in the graph is the water temperature delivered to the building.

Through the course of one day, that temperature varies from a low of 111 degrees F

to a high of 137 degrees F, a 26 degree swing. This indicates very poor temperature

regulation by the mixing valve.

Finally, the bottom line in the graph is the return recirculation water temperature.

This temperature falls to a low of 77 degrees F at about 4 am, indicating that water

users near the far end of the DHW supply line will experience very cool

temperatures during these periods. The spread between the delivered DHW

temperature to the building and the return water temperature indicates a very low

recirculation flow.

Figure 15: Domestic Hot Water System Temperatures at Glacier View for one day.

Operators can also use the measured data to help determine how much DHW

capacity needs to be available to serve peak loads. The Chugach Manor has two

instantaneous water heaters each able to supply 35 gallons per minute of domestic

hot water at an 80 degree temperature rise. Our flow meter data for a one month

period showed one ten minute period where the domestic hot water flow averaged

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10.5 gallons per minute. All other periods showed less usage. Figure 16 below

shows a Histogram of the DHW water usage rate measured in 10-minute intervals.

Clearly, one 35 gallon per minute water heater is sufficient to meet peak load and

the other water heater could remain off, saving 2 kW of pumping power that would

cost over $20,000 to operate over 10 years.

Figure 16: Distribution of DHW Flow Rates for the Chugach Manor, measured in 10-minute intervals. The peak flow rate observed is about 10.5 gallons/minute. Most periods have flow rates less than 8 gallons/minute.


Energy Managers can use the measured data to suggest to operators system

temperature adjustments that will reduce energy use, yet still maintain adequate

hot water supplies. For example, our measured data shows that the Chugach Manor

DHW temperature to the building is well regulated between 128 – 130 degrees F.

The temperature could be lowered to the 120 – 122 degree range, saving some

energy while still providing adequate hot water.

Energy Managers can do the careful analysis of flow data to suggest capacity

operating strategies that save energy and provide adequate hot water. Although

only one DHW flow meter was installed on this project, the data collected from the

facility is probably representative of other senior, multi-family facilities.

21

Extrapolation of that data to determine efficient operating strategies for other

facilities would be the role of an Energy Manager.


The DHW flow meter data can be used for much more accurate sizing of DHW

systems. Even if flow data is not available, the energy usage of a DHW system

broken into small time intervals provides good information about the required peak

sizing of the system. For the Glacier View system, no DHW flow meter was installed,

but the On/Off cycles of the circulation pumps feeding the indirect DHW tank are

being monitored. These cycle times can be correlated with boiler fuel use and then

used to determine the peak demand on the DHW system.

2.5 Ventilation System


For ventilation systems, possible parameters to monitor include:

The level of CO2, Relative Humidity, and VOCs present in the individual

spaces served by the ventilation system.

The same air quality parameters in the return air to the ventilation system,

which indicate the overall average of the parameters for all the spaces

ventilated.

The On/Off status of the ventilation system.

For this project, we planned to measure CO2 in individual spaces in the AHFC

Headquarters building and in the ventilated lounge areas of the Chugach Manor.

Monnit Inc. is releasing a line of wireless gas sensors that will eventually include a

CO2 sensor; however, release of that sensor was delayed until 4Q 2013. Instead we

are building CO2 space sensors that utilize a CO2 sensor that produces an analog

voltage output connected to a Monnit wireless voltage sensor. This assembly

requires connection to 120 VAC power, so is less ideal than the forthcoming Monnit

CO2 sensor.

Monnit does currently offer a wireless relative humidity sensor, but we did not

choose to monitor relative humidity for this project.

For the AHFC Headquarters building, the building automation system does have CO2

and relative humidity sensors in the return air back to the rooftop air handler unit.

These quantities are being exported to the BMS database.

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To record the On/Off status of the ventilation unit, a relay connected across power

to the ventilation unit will close a set of contacts when the ventilation unit is on.

Those contacts can be connected to a Monnit Dry Contact sensor. For buildings

where data from the building automation system is available, such as the AHFC

Headquarters, the status of the ventilation system can be acquired from that source.

2.5.2 Benefits to Building Operators and Energy Managers

Building operators and energy managers need to work together to ensure adequate

but not excessive ventilation airflows. Most commercial buildings in Alaska with

mechanical ventilation systems have excessive outside air ventilation, as indicated

by CO2 levels far less than 900 ppm. Substantial energy is wasted heating excessive

outside air. Some schools in Rural Alaska spends hundreds of thousands of dollars

per year heating up outside ventilation air. However, it is important to measure IAQ

parameters for individual spaces, as some spaces may not be over-ventilated despite

the fact the building as a whole is.

Adjusting the amount of ventilation air to spaces depends on the type of ventilation

system being used. For a building such as the AHFC Headquarters, which has a

Variable Air Volume HVAC system, ventilation airflows to each space can be

controlled by adjusting the minimum primary air stop on the VAV box serving the

space. Also during some times of the year, the overall outside air flow to the

building is determined by the minimum stop on the outside air damper. That setting

may require adjustment. The process of tuning ventilation air flows can be quite

complicated, but the rewards can be large. Measured IAQ data from spaces in the

building is a very important ingredient in the process.

The Chugach Manor has a number of ventilation units that operate on a 24/7

schedule serving the lounges and hallways. Collecting occupancy data (currently

underway) and CO2 data could help tune up those systems to more appropriate flow

rates and operating schedules.

Figure 17 below is an example of ventilation system operating schedule data

collected from the AHFC Headquarters. The figure shows the operating flow rate

(measured 0 – 100%) of the main air handler fan, but the flow rate is shown across

each hour of the day. There are two lines shown on the graph, one for Monday-

Friday and one for Saturday-Sunday. The graph shows that a nighttime shutdown of

the system occurs during the weekdays, but no nighttime shutdown is occurring on

the weekends. Substantial energy could be saved by implementing some shutdown

periods of this 80 kW load on the weekend. 12 hours of shutdown per weekend day

23

would save over $10,000 per year in electricity costs. More than 12 hours per

weekend day is probably possible resulting in even larger savings.

Figure 17: AHFC Headquarters Rooftop Supply Fan flow rate by hour and day type.


By looking at IAQ data and ventilation flow rates from existing systems, designers

should be able to more appropriately size and control new systems. In addition,

measured data will illustrate the importance of having ventilation rates respond to

occupancy, as rarely does a building require the design level of ventilation capacity.

2.6 Cooling System


Mechanical cooling is present in Alaskan commercial buildings with high internal and

solar gains, such as office buildings. From an energy efficiency perspective, probably

the most important aspect of the cooling system to monitor is the operation of the

“economizer” cycle. The economizer cycle uses outside air, when cool enough, to

offset or meet the entire cooling load of the building. Use of outside air for cooling

reduces the electricity use of the mechanical chiller or air conditioner.

24

The following parameters are useful to monitor:

Temperature of the outside air flowing through the outside air damper.

Relative humidity of outside air.

Temperature of the return air coming from the building.

Temperature of the mixed air, which is a mixture of the return air and

outside air.

Temperature of the supply air delivered to the building.

If the cooling system is a variable air volume system, the flow rate of the

main supply fan.

For this project, we focused on monitoring the cooling system at the AHFC

Headquarters. The above parameters were exported from the building automation

system and stored in the BMS database.


By examining the above temperatures under a variety of conditions, the proper

operation of the economizer can be verified. The mixed air temperature should

track the outside air temperature during summer periods when the outside air is

cooler than the return air.2

Beyond verifying proper operation of the economizer cycle, an energy manager can

investigate the potential to modify the control strategy for the building’s supply air

temperature. If the cooling supply air temperature can be raised while still meeting

cooling loads, the use of the mechanical cooling equipment will be diminished

because a higher fraction of the cooling load will be met through use of outside air.3

Data collected so far at the AHFC Headquarters indicate that some modification of

the supply air setpoint program may be possible and result in energy savings. At the

moment this is being written, the supply air temperature at the Headquarters is 53

degrees F. However, the main supply fan is running only at 70% capacity. If the

supply air temperature were raised a few degrees, the supply air fan could ramp up

and provide the same total level of cooling to the building. By raising the supply air

2 During periods when outside air is cooler than the desired supply air temperature, the mixed air temperature

should be at the desired supply air temperature. That mixed air temperature is achieved by a proper mixing of outside air and return air. 3 An example will help illustrate this point. If the return air from the building is at 75 deg F, outside air is at 60 deg

F and the supply air to the building is at 50 deg F, outside air is meeting 60% of the cooling load: (75 – 60)/(75 – 50) = 60%. If the supply air temperature can be raised to 55 deg F and still meet loads, outside air will be meeting 75% of the total cooling load: (75 – 60)/(75 – 55) = 75%. This ignores latent cooling loads; considering those will make the savings larger.

25

temperature, outside air (currently at 61 degrees F) would provide a higher fraction

of the total cooling, reducing mechanical cooling electricity use.


The measurements discussed above allow for a reasonable estimate of the cooling

load of the building. Assuming measurements are taken during periods similar to

design outdoor conditions, an estimate of the peak cooling load can be made, which

can then be used for cooling equipment sizing when an HVAC renovation occurs.

2.7 Space Temperatures


Space temperatures are easily monitored with a Monnit wireless temperature

sensor or by exporting from the building automation system if possible. At the AHFC

Headquarters building, we are collecting a number of space temperatures through

export from the automation system.


Space temperatures can help a building operator determine whether heating and

cooling systems are balanced properly. Energy managers can verify whether

unoccupied temperature schedules are being implemented correctly and whether

energy saving adjustments are possible. As an example, Figure 18 below shows the

temperatures for one warm weekday for one of the monitored spaces in the AHFC

Headquarters building. A number of things can be learned from the data. The space

temperature at midnight at the left of the graph is relatively high, indicating that the

unoccupied schedule is working and allowing the space to overheat while no

occupants are present. At about 3 am, the building air handler starts up and cools

the space to the occupied setpoint. For this space, the occupied temperature

setpoint of about 72 degrees is reach by about 4:30 am. Checking the other space

temperatures we are monitoring indicates that all reach their occupied setpoint by

5:30 am at the latest. Since occupants do not arrive until approximately 7:30 am,

there is probably the potential to delay this startup schedule and reduce the energy

cost of running the air handler. However, additional space temperatures should be

examined before implementing the change.

At about 5:30 pm, you see the building enter unoccupied mode and the temperature

in the space rises. The air handler cycles On a couple of times during the evening,

temporarily lowering the space temperature.

26

Figure 18: Temperature of one space at the AHFC Headquarters for one warm summer weekday.

2.8 Space Lighting Levels


We used two different Monnit wireless sensors to monitor light levels in spaces: a

Light On/Off sensor and a Lux (Light Level) sensor. The Light On/Off sensor only

indicates whether lights are On or Off, whereas the Lux sensor gives a continuous

light level measurement. In the future we will probably only deploy the Light Level

sensors, as they provide more information than the Light On/Off sensor and still can

be used to determine if artificial lights are On or Off.

Because we were interested in determining the contribution that natural light is

making toward lighting requirements, we placed the Light Level sensors on desktops

with the sensor surface horizontal. Velcro was used to keep the sensor from

accidentally being moved.


The light level sensors give information about how often the artificial lights are On

and also give information about the amount of natural lighting available. Figure 19

below shows the light levels measured in one office on the south side of the AHFC

headquarters building during one weekday. Starting at midnight on the left, the

27

artificial lighting was On for some time in the middle of the night, presumably due to

cleaning personnel. The lights were turned on for the normal workday at about 6:40

am. The build-up in light levels is due to natural light; the graph shows that natural

light provides as much light as artificial light during the period from about 9:30 am

until 6 pm on this particular day, indicating a large daylighting potential for this day.

Artificial lights go off at about 7 pm, but then back on shortly thereafter. Another

short off/on cycle occurs at 9:30 pm, and then off at 11:30 pm for the rest of the

shown period. During this day, artificial lights were on for approximately 16.5 hours.

Although we did not have an occupancy sensor in this space, it is unlikely the space

was occupied for more than 9 hours. Improved lighting controls would have a

relatively large impact here, although obviously the rest of the data should be

examined.

Figure 19: Light Levels for one weekday measured in a south side office at the AHFC Headquarters. The maximum value read by the sensor is 1500 Lux, causing the plateaus observed in this graph.


This data should help designers of new or renovated lighting systems estimate the

benefits from improved lighting controls and natural lighting strategies.

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2.9 Space Occupancy


For this project, we used Monnit Wireless Infrared Motion Sensors to record when

spaces were occupied.


For building operators, the occupancy data can be used to adjust occupied /

unoccupied schedules to better match actual occupancy.


Actual occupancy data will allow energy managers to determine the cost-

effectiveness of installing occupancy sensors to control lights, or installing

scheduled-based controllers for controlling loads currently operating 24/7. In

addition, the occupancy data will help managers suggest adjustments to existing

schedule-based controllers.

Here are some examples of data already collected and some energy-saving

improvements suggested by the data. An occupancy sensor was installed in the 2nd

floor hallway of the Chugach Manor in a high traffic area near the elevator. From

one month of collected data, the average occupancy of the hallway was 35%.

Hallway lights are on continually. An energy-saving strategy would be to leave some

of the lights on continually but control the rest with occupancy sensors. Doing so

would save a minimum of 65% of the energy use of the controlled fixtures, since

most fixtures are in areas of lower traffic than where our occupancy sensor was

located.

Figure 20 shows the average occupancy of the 3rd floor Billiards lounge at the

Chugach Manor. Most of the use is concentrated between 8 am and 10 pm. The

HVAC unit supplying that space currently runs 24/7 (it also supplies the 2nd floor

lounge, which has a similar but lighter schedule of occupancy). Installing a schedule-

based controller for that unit could save substantial energy. The controller would

need an override for when the space requires heating during the unoccupied period.

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Figure 20: Occupancy Fraction of the 3rd Floor Billiards Lounge at the Chugach Manor, by hour of the day.


The actual occupancy data should help designers do cost/benefit analysis of

installing occupancy-based control systems in their new construction and renovation

projects.

2.10 Snowmelt Systems


Sidewalk snowmelt systems uses very high amounts of energy, and the control

systems that operate them often malfunction or are bypassed. Monitoring the

energy use of these systems allows building operators and energy managers to

quickly detect energy-wasting operations.

For this project we monitored one of the two snowmelt systems at the Chugach

Manor, the one serving the back sidewalk. The following monitoring approach was

used:

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Make a one-time measurement of the flow rate of glycol to the sidewalk

when the circulation pump is On. When the pump is on, the flow rate is

relatively constant under normal operation, as the circulation pump is a fixed

flow rate pump.

Install a sensor to detect when the circulation pump is On. We used a

Monnit Voltage Detect sensor across the pump power leads, but a relay

across those leads with a Monnit Dry Contact sensor could also be used.

Install a Monnit temperature sensor on the warm supply pipe to the sidewalk

and another temperature sensor on the cool return pipe from the sidewalk.

These sensors allow the determination of the energy use of the system, by assuming

the flow rate equals the value measured in the one-time test when the circulation

pump is on.

Because we have had good luck with the inexpensive ultrasonic flow meters used

elsewhere in this project, another approach to monitoring a snowmelt system would

be use of an ultrasonic flow meter. These flow meters (model TUF-2000, various E-

bay sellers) can also act as Btu meters, as they have input terminals for warm and

cold temperature sensors. The meter can be directly configured to measure Btus

and emit a pulse (contact closure) every time 1,000 Btus is used by the snowmelt

system. A Monnit pulse counter sensor can be connected to pulse output of the

meter to transmit the measurement.

The advantage of the flow meter approach is that it will accurately account for

situations where the flow in the system is not at its normal value. While monitoring

other snowmelt systems, we have observed periods of low flow when air has been

introduced into the system or when some of the snowmelt loops are not

functioning. Also, there is some variation in flow rate with the temperature of the

glycol, as glycol becomes more difficult to pump at lower temperatures. Another

advantage of this approach is that no electrician is required for installation; with the

prior approach, monitoring the On/Off cycles of the circulation pump requires

connecting a sensor to the high-voltage pump wires.


An out-of-control snowmelt system can use over $2 of energy per year per square

foot of sidewalk melted (natural gas). So, a 5,000 square foot sidewalk will cost over

$10,000 per year of energy. Proper control of the system can reduce this energy

cost in half. Staff should monitor the system energy use to ensure that usage lowers

during periods of no snow. Staff should experiment with adjusting idle temperature

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settings downward to reduce energy use while attempting to maintain adequate

performance.


Snowmelt monitoring data should help designers understand the energy cost of

utilizing snowmelt and allow them to assess accurately other alternative options

(e.g. building coverage over sidewalk areas). Data of the reliability of snowmelt

control systems should also be useful to designers, so that simple-to-operate and

reliable controls can be installed on new systems.

3. Internet Access and Network Impact Issues

The monitoring equipment used for this project is connected to the Internet so that measured

values can be observed shortly after they occur. This real-time access provides many benefits

relative to systems where measured data is only periodically downloaded and made available.

So, access to the Internet is essential at the facilities that are being monitored.

Three primary options exist in Alaska for connecting monitoring devices to the Internet:

Use an existing Internet-connected

network in the facility.

Establish a new Internet connection in

the facility using a wired Internet access

technology such as a cable modem

(provided by the Cable TV company, GCI)

or a DSL modem (provided by the local

phone company).

Establish a new Internet connection in

the facility using a wireless Internet

access technology, such as a wireless

cellular network.

For this project, we used the latter two methods

to provide Internet access to our monitoring

equipment. In the AHFC Headquarters building,

a new cable modem from GCI was installed, and

Ethernet wiring was installed from that modem

to our three Monnit sensor gateways. The cable

modem is currently dedicated to providing Internet access to our monitoring system.

Figure 21: Cellular Router (left) providing Internet Access to a Monnit Sensor Gateway (right) at the Chugach Manor.

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Internet Access Method Monthly

Cost

Lifecyle Present

Value cost over 10 years

Use Existing Internet Network in Facility

$0 / mo $0

Cellular Internet $10 / mo $1,000 Cable or DSL Internet $40 / mo $3,990

In Chugach Manor and Glacier View, GCI’s wireless cellular network was used to provide

Internet to the Monnit sensor gateways through use of a Cradlepoint cellular router. Figure 21

shows a picture of the Chugach Manor installation. The Cradlepoint cellular router is the

sizable box on the left and the Monnit sensor gateway is the box on the right. The Cradlepoint

router provides Internet access to the sensor gateway by a simple Ethernet cable connection

between the two.

Monnit will have a Cellular GSM Sensor Gateway available by the end of 2013, which should

eliminate the need for the Cradlepoint router. Instead, a GSM SIM card (GCI and AT&T are GSM

cellular carriers in Alaska) is inserted directly into the sensor gateway, and the gateway

connects directly to the cellular data network.

In terms of the geographic availability of the access approaches, most Alaskan communities

with more than 2,000 people have access to DSL, cable, and cellular internet services. In small

rural communities, DSL is generally available, and cellular data service is now present in more

and more rural communities, due to

GCI building out their wireless

network in many small communities.

The monthly cost of Internet access

is a very significant component of

the lifecycle cost of a monitoring

installation. Table 1 compares the

costs of three different access

approaches. Using an existing

network in the facility incurs no

additional monthly cost, so is clearly the least expensive option. GCI offers a low usage (300

MB / month) wireless data plan sufficient for a building monitoring system for $10/month that

is next most cost-effective option. Over a 10 year period, this cost amounts to $1,000 present

value. Finally, using DSL Internet access from the local phone company or utilizing cable

modem access from the cable TV company results in the highest cost. The 10 year present value

cost of this option is a very high $3,990, which can easily exceed the cost of the sensor

equipment for small to moderate size installations.

Although using an existing Internet network in a facility is the least expensive option, some

organizations including AHFC have concerns about the security impacts of attaching additional

devices to their network. The Monnit sensor gateway does not require any ports to be opened

allowing inward access from the Internet to the gateway device. However, it is an additional

network-connected device containing a processor that could conceivably run malicious code.

Although AHFC IT staff indicated that testing of the Monnit sensor gateway and configuration of

Table 1: Ongoing Internet Access Costs for different Access Methods.

33

their firewalls and proxy servers could possibly result in allowance of the gateway on their

network, there was no willingness to pursue that option. Instead, separate standalone

networks were built to provide Internet access to the sensor gateway.

4. Scope and Costs for Future Buildings

Our recommendations for future installation of energy monitoring equipment in AHFC facilities

are presented in this section. First, we recommend a gradual approach to monitoring the

remaining AHFC facilities. Experience is still being acquired from this project, so expanding the

effort at a moderate pace should be favored relative to a highly accelerated deployment.

Below is our recommended list of buildings that should be targeted for energy monitoring, in

priority order:

1. Buildings Scheduled for a HVAC Renovation in the Near Future: If heating systems or

domestic hot water systems are scheduled to be replaced soon in a building, an energy

monitoring effort will provide important data for sizing those new systems. Without

actual energy usage data, HVAC systems tend to be substantially oversized. By basing

sizing on actual energy usage, substantial capital costs and energy costs can be realized.

The capital cost savings from right-sizing HVAC systems will very likely more than offset

the cost of the energy monitoring effort.

2. Buildings with High Total Energy Costs: The cost of performing energy monitoring is

relatively fixed and does not vary much with the size of the systems being monitored.

Therefore, the monitoring cost is a small fraction of the energy cost of a high energy use

building. Even if the monitoring effort identifies only small percentage savings

opportunities in these buildings, the cost of monitoring will likely be justified. Utility bill

analysis can be done to identify high energy use buildings.

3. Buildings with High Energy Use per Square Foot when Compared Against Their Peer

Group: When comparing buildings of a similar type, those with high normalized energy

use are probably the buildings that have the largest potential for energy savings and

have the largest potential for energy monitoring benefits. Energy use should be

normalized for the size of the building (per square foot) and, if the energy use involves

space heating, should be normalized for heating degree-days. Utility bills can be used to

do this screening.

4. Buildings with Systems that have been shown to Benefit from Monitoring: Mechanical

Ventilation Systems, Sidewalk Snowmelt Systems, and Buildings that are heavily

dependent on Automatic Controls to Schedule Energy-Using Systems: These three

system types have been shown to realize benefits from energy monitoring for the

following reasons. Mechanical ventilation systems are very often over-sized and deliver

34

too much outside air for standard occupancy conditions. Monitoring space CO2 levels

and then adjusting the ventilation system to provide an appropriate amount of air can

realize substantial heating energy use reductions. Sidewalk snowmelt systems use large

amounts of energy and the systems that control the amount of heat delivered to the

sidewalk are often adjusted in an energy-inefficient manner. In addition, mixing valves

and snowfall sensors frequently fail. Energy monitoring will identify these problems

quickly. Finally, buildings that rely on sophisticated controls to schedule energy-using

equipment often exhibit problems with the control system due to manual bypass or

poor configuration. Equipment will often be found erroneously operating during

unoccupied periods. Some simple monitoring can detect many of these problems.

The above list gives guidance on which buildings to target for energy monitoring. After

selecting buildings, the next step is to determine what type of monitoring to do within the

building. A large benefit of the technology used in this project is the ability to easily add

additional sensors to a building’s monitoring system. Thus, a basic monitoring system can be

installed, and additional sensors can be added in the future if the basic monitoring identifies

issues that require more detailed monitoring. A Monnit wireless sensor gateway has the ability

to accommodate up to 100 sensors, so gateway capacity should not be an issue. Configuration

of a new sensor does not require any on-site configuration; all configuration can be done

remotely through the iMonnit web portal prior to installing the sensor on–site.

The two tables below give our recommendations for basic energy monitoring equipment and

sensors. The first table lists equipment that should be installed in every monitored building.

The second table gives additional sensors that are valuable in some of the monitored buildings.

Budgetary costs per building are provided for each item, and these estimates were developed

using our experience from this project.

Table 2: Monitoring Equipment/Services for All Monitored Buildings

Item Details Cost

Site Assessment Initial site visit that determines installation specifics for equipment and sensors.

$400

Mobilization / Demobilization for Equipment Installation

Local travel to the site (not including travel to remote cities), gaining access to needed areas of the facility, etc.

$150

Wireless Sensor Gateway + Cellular Router for Internet Access

A sensor gateway is needed to transmit sensor readings to the Internet. Internet Access is required for the gateway and is assumed to be provided by a Cellular Router using a wireless data plan.

$970

35

Item Details Cost

Whole-Building Fuel Meter

See section 2.1 for benefits of monitoring the building’s fuel use. Electricity monitoring is presented in the next table.

$1,050 per Natural Gas or Oil Meter. Sometimes multiple oil meters are required if there are dedicated fuel lines for each boiler.

Space Heating Health Monitor

Usually, a temperature sensor on the Heating Distribution loop is sufficient. A low-temperature notification can be set up, although a seasonal adjustment in the alarm temperature may be required. Sometimes, boilers have alarm contacts that can be monitored. See section 2.2 for benefits.

$270 per temperature or alarm contact monitoring point. For the most affordable approach, one temperature point could be monitored initially and more points added later.

Domestic Hot Water Health Monitor

A temperature sensor on the domestic hot water pipe to the building should be sufficient. See section 2.4 for benefits.

$270 for one temperature monitor.

Supply and Return Temperatures on Space Heating Distribution Loop

Most space heating distribution circulation pumps are very over-sized. My monitoring the temperature difference across the loop during heating design conditions, the degree of oversizing can be assessed, and an energy-saving replacement can be recommended.

If the Distribution Supply temperature is already being monitored for Space Heating Health (above), only one more $270 temperature point is needed for the Return temperature.

Table 3: Monitoring Sensors that are Applicable to Some Monitored Buildings.

Item Details and When Applicable Cost

Whole-Building Electric Meter Sensor

Recommended for buildings where electricity usage is moderate to high and AHFC has options to control electricity use (as opposed to controlled by tenant actions). Also recommended for buildings in areas where the electric utility has low fees for installing a pulse output unit on their meter.

Cost varies significantly with the charges levied by

the electric utility for installing a pulse output

device on the electric meter ($480 Fairbanks

GVEA to $1,700 Anchorage ML&P). Total

Cost varies from $1,200 to $2,500.

36

Item Details and When Applicable Cost

Space Temperature Monitoring

For buildings where AHFC has control over space temperatures and those temperatures are varied on a schedule, space temperature monitoring is valuable to ensure that the temperature control schedule is working properly.

$230 per temperature point. Number of

recommended points depends on building size.

Space CO2 Monitoring Recommended for buildings that have mechanical ventilation systems delivering 150 cfm or more of outside air. See section 2.5 for benefits.

$480 per CO2 point. Number of recommended

points depends on building size.

Sidewalk Snowmelt Monitoring

Recommended for any buildings with 500 square feet or more of sidewalk snowmelt. See section 2.10 for benefits.

We recommend the BTU meter approach, utilizing an ultrasonic flow sensor. Total Cost is $1,500 per snowmelt system.

As data from the above recommended sensors is collected, issues will be identified that can

justify more detailed monitoring. Because of the ease of expanding this monitoring system,

additional monitoring can occur at reasonable cost.

5. Use of Smart Meters for Acquiring Data

Smart Meters are utility meters that record utility usage (usually electricity but sometimes fuel)

in intervals of an hour or less and communicate that information back to the utility company

(smart meters also have other features). If a smart meter exists at a facility, then it may be

possible to automatically retrieve that energy consumption data from the utility company

across the Internet instead of installing a new sensor at the facility to acquire the data. Cost

savings could result; for example, the total cost of monitoring the electric meters at the AHFC

Headquarters and the Chugach Manor was about $2,500 per meter. Retrieving smart meter

data across the Internet would only involve configuration costs, so should be less expensive.

We contacted the Regulatory Commission of Alaska, Chugach Electric, and Municipal Light and

Power to see if any Smart Meters were being deployed in Alaska. The individuals contacted

were not aware of any Smart Meter deployments. If such programs occur in Alaska, this will

allow for substantial cost savings in future energy monitoring projects.

37

6. Utilization of BUDS and ARIS Projects for Data Collection and Storage

The Building Utility Data System (BUDS) project funded by AHFC investigated a wireless sensor

data collection system for collecting building energy and environmental data. The BUDS design

relies on use of Digi wireless sensor products. However, the Digi wireless sensor products have

now been discontinued; the focus of the Digi company is on sale of RF modules that can be

incorporated into other companies’ products. So, the data collection design and software tools

developed for the BUDS project were not applicable to this project. The BUDS report does

provide some good information about sensors and signal conditioning circuits that is generally

applicable to other data acquisition systems.

The Alaska Retrofit Information System (ARIS) is a comprehensive database of energy rating

and energy use data for Alaskan buildings. The database does have data structures developed

for the purpose of storing building sensor data. Because of the short timeframe for this project,

it was more expedient to utilize a separate database for storing sensor data. However, it

would not require much additional effort to forward the sensor data to the ARIS database for

storage there, where it would be available along with the other forms of building data available

in ARIS. Somewhat more effort would be required to make ARIS be the primary and only

storage location for sensor data. The database storage and retrieval code used for the current

project was partitioned into separate modules. This design approach does facilitate changing

the database backend of the application, for example, changing the sensor database to utilize

ARIS.

7. Remote Control of Systems, Task 12

This project’s RFP requests information on how to best remotely control pumps and motors.

The primary emphasis of this project was monitoring, and the equipment selected for the

project currently only has monitoring capabilities. Monnit does have a very simple relay

control module under development, which may be suited for some simple control tasks

when it is released. If AHFC desires to remotely control motors and pumps with currently

available technology, use of a small Internet-connected DDC control system is probably the

best approach.

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8. Appendix: Measured Values

This appendix lists the all of the measured values collected by this project, showing the location

of the sensor and type of sensor technology used. The lists are organized by building.

Table 4: Measured Values for Chugach Manor

Sensor Name Location Sensor TypeWeather

Anc Merrill Field Temp Merrill Field Airport, Anchorage National Weather Service Internet

Access

Anc Merrill Field Wind Speed Merrill Field Airport, Anchorage National Weather Service Internet

Access

Utilities/Fuel

Gas Meter Southside of building, outside of building, East wing MVP-10 Natural Gas Meter Pulser +

Monnit Pulse Count Sensor

Electric Meter Southside of building, outside of building, near Electrical

room.

KYZ Pulser on Electric Meter +


Space Heating

Heating Supply T Northeast corner of 3rd Floor Boiler Room Monnit Probe Temperature Sensor

East Heating Return T Northeast corner of 3rd Floor Boiler Room Monnit Probe Temperature Sensor

West Heating Return T Northeast corner of 3rd Floor Boiler Room Monnit Probe Temperature Sensor

Domestic Hot Water

DHW Flow Rate Northeast corner of 3rd Floor Boiler Room TDS-100M Ultrasonic Flow Meter +

Monnit Pulse Counter Sensor

DHW Cold Temp Northeast corner of 3rd Floor Boiler Room Monnit Probe Temperature Sensor

DHW to Bldg T Northeast corner of 3rd Floor Boiler Room Monnit Probe Temperature Sensor

DHW Recirc Return T Northeast corner of 3rd Floor Boiler Room Monnit Probe Temperature Sensor

Space Conditions, Occupancy

Occup 1 State - 3rd Lounge 3rd Floor Billiards Lounge, on South Wall Monnit Infrared Motion Sensor

Occup 1 Fraction - 3rd Lounge 3rd Floor Billiards Lounge, on South Wall Calculated from Occup 1 State

Occup 2 State - 2nd Hallway 2nd Floor Lounge, on North Wall Monnit Infrared Motion Sensor

Occup 2 Fraction - 2nd Hallway 2nd Floor Lounge, on North Wall Calculated from Occup 2 State

Occup 3 State - 2nd Lounge 2nd Floor Hallway, West Wing, near elevator, mounted

on ceiling

Monnit Infrared Motion Sensor

Occup 3 Fraction - 2nd Lounge 2nd Floor Hallway, West Wing, near elevator, mounted

on ceiling

Calculated from Occup 3 State

Snowmelt

Back Snowmelt Circ Pump On/Off 1st Floor Mechanical Room, West Wing, South Wall Monnit 240 VAC Voltage Detection

Sensor

Back Snowmelt Circ Pump Runtime 1st Floor Mechanical Room, West Wing, South Wall Calculated from Circ On/Off

Back Snowmelt to Slab T 1st Floor Mechanical Room, West Wing, South Wall Monnit Probe Temperature Sensor

Back Snowmelt from Slab T 1st Floor Mechanical Room, West Wing, South Wall Monnit Probe Temperature Sensor

Gateways and Repeaters

Chugach Manor Gateway Northeast corner of 3rd Floor Boiler Room Monnit Ethernet Gateway +

Cradlepoint MBR95 Cellular Router

+ Huawei E220 Cellular Data Modem

East Repeater 3rd Floor Laundry room, East Wing, above Washer Monnit Repeater

West Repeater 3rd Floor Hallway, West Wing, between elevators and

Laundry Room, closer to Laundry room, Northside power

outlet

Monnit Repeater

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Table 5: Measured Values for AHFC Headquarters

Sensor Name Location Sensor Type

Weather

Boniface/Tudor Temp Alaska Science Center on APU Campus Weather Undergroud API

Boniface/Tudor Wind Speed Alaska Science Center on APU Campus Weather Undergroud API

Utilities/Fuel

Gas Meter NW Corner, outside of building MVP-10 Natural Gas Meter Pulser +


Electric Meter SW Corner, ouside of building KYZ Pulser on Electric Meter +


Rooftop Unit

Return Air CO2 Rooftop HVAC Unit Exported from Building

Automation System (BAS)

Return Air Humidity Rooftop HVAC Unit Exported from BAS

Return Air Temp Rooftop HVAC Unit Exported from BAS

Rooftop Outside Air Temp Rooftop HVAC Unit Exported from BAS

Outside Air Damper Position Rooftop HVAC Unit Exported from BAS

Mixed Air Temp Rooftop HVAC Unit Exported from BAS

Supply Fan VFD % Rooftop HVAC Unit Exported from BAS

Supply Discharge Air Temp Rooftop HVAC Unit Exported from BAS

Supply Discharge Air Setpoint Rooftop HVAC Unit Exported from BAS

Space Conditions, Temperature

207b South Temp VAV Terminal 207b, South office, 2nd Floor Exported from BAS

215 West Temp VAV Terminal 215, West office, 2nd Floor Exported from BAS

209 Scott Temp VAV Terminal 209, Scott Waterman office, 2nd Floor Exported from BAS

202 North Temp VAV Terminal 202, North office, 2nd Floor Exported from BAS

204 East Temp VAV Terminal 204, East office, 2nd Floor Exported from BAS

207a Southeast Temp VAV Terminal 207a, Southeast office, 2nd Floor Exported from BAS

210 Interior Space Temp VAV Terminal 210, Interior office, 2nd Floor Exported from BAS

Space Conditions, Light

Light Level #1 - South Eric Eric ?? Office, south side 2nd Floor, on desk Monnit Lux Light Level sensor

Light Level #2 - West Dena Dena Strait Office, West side 2nd floor, on desk Monnit Lux Light Level sensor

Light Level #3 - North Tom Tom McLaughlin Office, North side 2nd floor, on desk Monnit Lux Light Level sensor

Light Level #4 - East Rosie Rosie Ricketts Office, North side 2nd floor, on desk Monnit Lux Light Level sensor

Light Level #5 - Southeast Phil Adams Phil Adams Office, Southeast corner 2nd floor, on desk Monnit Lux Light Level sensor

Light On/Off #1 - R2D2 Conference R2D2 Conference Area, on wall on West side. Monnit Light On/Off sensor

Light On/Off #2 - 1st Training Rm 1st Floor Training Room, East Wall above door. Monnit Light On/Off sensor

Space Conditions, Occupancy

Occup 1 State - 2nd Men Bath 2nd Floor Men's Bathroom. Monnit Infrared Motion Sensor

Occup 1 Fraction - 2nd Men Bath 2nd Floor Men's Bathroom. Calculated from Occup 1 State.

Occup 2 State - 1st Training Rm 1st Floor Training Room, East Wall, by doorway. Monnit Infrared Motion Sensor

Occup 2 Fraction - 1st Training Rm 1st Floor Training Room, East Wall, by doorway. Calculated from Occup 2 State.

Occup 3 State - Scott Office Scott Waterman's office, 2nd floor. Monnit Infrared Motion Sensor

Occup 3 Fraction - Scott Office Scott Waterman's office, 2nd floor. Calculated from Occup 3 State.

Space Conditions, HVAC

Building Avg Cooling Demand Calculated from all VAV terminal values. Exported from BAS

Bldg Avg Heating Demand Calculated from all VAV terminal values. Exported from BAS

209 Scott Cooling Demand Scott Waterman's office, 2nd floor. Exported from BAS

209 Scott Heating Demand Scott Waterman's office, 2nd floor. Exported from BAS

Vertical South Solar Window sill, middle of south side of building on 2nd

Floor.

Monnit Lux Light Level sensor

coated with black fingernail polish

to reduce sensitivity


Gateways A gateway in each Telecomm closet on the 1st, 2nd, and

3rd Floors.

Monnit Ethernet Gateways

1st Floor Repeater Ray Rouzan's office, east wall power outlet. Monnit Repeater

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Table 6: Measured Values for Glacier View

Sensor Name Location Sensor Type

Weather

Seward Airport Temp Seward Airport National Weather Service Internet

Access

Seward Airport Wind Speed Seward Airport National Weather Service Internet

Access

Utilities/Fuel

Fuel Boiler #1 Next to Boiler #1, near floor Elster 4p Fuel Flow Meter + Monnit

Pulse Counter Sensor

Fuel Boiler #2 Next to Boiler #2, near floor Elster 4p Fuel Flow Meter + Monnit

Pulse Counter Sensor

Total Fuel Calculated from Fuel #1 and #2 Calculated from Fuel #1 and #2

Space Heating

Bldg Heating Supply T North East corner of boiler room Monnit Probe Temperature Sensor

Space Distribution Delta-T North wall of boiler room in same enclosure as Space

Distribution flow meter.

Delta-T circuit using AD592

temperature sensors, connected to

Monnit 1.25VDC Analog Sensor

Space Distribution Flow North wall of boiler room TUF-2000 Ultrasonic Flow Meter +

Monnit Pulse Counter Sensor

Domestic Hot Water

DHW Temp from Tanks Behind DHW Storage Tanks Monnit Probe Temperature Sensor

DHW Temp to Bldg Behind DHW Storage Tanks Monnit Probe Temperature Sensor

DHW Return Temp Behind DHW Storage Tanks Monnit Probe Temperature Sensor

DHW Tank #1 Top T On top of DHW Tank #1 Monnit Probe Temperature Sensor

DHW Circ #1 On/Off Mounted on Circ Pump electrical junction box on East

wall

Functional Devices RIBU1C relay

conntected to Monnit Dry Contact

sensor

DHW Circ #1 Runtime Calculated from Circ #1 On/Off Calculated from Circ #1 On/Off

DHW Circ #1 Return T On return pipe behind DHW Tank #1 Monnit Probe Temperature Sensor

DHW Circ #2 On/Off Mounted on Circ Pump electrical junction box on East

wall

Functional Devices RIBU1C relay

connected to Monnit Dry Contact

sensor

DHW Circ #2 Runtime Calculated from Circ #2 On/Off Calculated from Circ #2 On/Off

DHW Circ #2 Return T On return pipe behind DHW Tank #2 Monnit Probe Temperature Sensor

Boiler

Boiler #1 Alarm Wireless sensor mounted on top boiler #1 behind Energy

Manager controller

Monnit Dry Contact sensor

connected to Alarm terminals on

Boiler #1 Energy Manager controller

Boiler #1 On/Off Wireless sensor mounted inside burner #1 enclosure Functional Devices RIBU1C relay

connected across burner #1 fuel

valve with contacts connected to


Boiler #2 Alarm Wireless sensor mounted on top boiler #2 behind Energy

Manager controller


connected to Alarm terminals on

Boiler #1 Energy Manager controller

Boiler #2 On/Off Wireless sensor mounted inside burner #2 enclosure Functional Devices RIBU1C relay

connected across burner #2 fuel

valve with contacts connected to


Primary Loop T Behind Boilers on Primary Loop Monnit Probe Temperature Sensor

Blr Rm Cooing Fan Runtime Mounted on Housing of Boiler Room Cooling Fan Monnit Activity Timer Sensor


Glacier View Gateway North wall of boiler room Monnit Ethernet Gateway +

Cradlepoint MBR95 Cellular Router +

Huawei E220 Cellular Data Modem

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9. Appendix: Monitoring Installation Notes and Issues

In this appendix, we describe a number of in-the-trenches details concerning the monitoring

technologies used in this project. The notes are organized by product.

9.1 Monnit Wireless Sensors

9.1.1 General Issues

Lithium Battery Issues: We intended to use Energizer Ultimate Lithium AA

batteries to power the sensors. These batteries have very low self-discharge

current and will potentially allow sensors to operate 10+ years without

battery changes. Also, these batteries function at temperatures down to -40

degrees F. However, Monnit wireless sensors manufactured prior to July 11,

2013 (all of the sensors used in this project) have a high voltage battery

cutoff that cause the sensor to not operate if battery voltage is too high. In

warm environments, the Energizer Ultimate batteries can exceed this

threshold and cause the sensor to not operate. Therefore, we switched back

to conventional Alkaline AA batteries for indoor sensors, and only used

Energizer Ultimate Lithium batteries for outdoor sensors. Replacement

batteries for the sensors deployed in this project should follow this rule.

Future sensors will not have this issue and can use the Energizer Ultimate

batteries in all situations.

Adding New Sensors: When adding a new sensor to the system, the Monnit

Sensor Gateway needs to learn about the new sensor. Twice per day it

downloads its current sensor list from the Monnit server. This may cause a

delay in when you see data from a new sensor added to the system. You can

force the gateway to download its current list of sensors by removing power

from the gateway for 5 or more seconds and then repowering the gateway.

This power cycle will cause the gateway to download its current sensor list.

Sensor Testing: We found it useful to use a Monnit USB Gateway to test

sensors before deploying them. We assign the USB gateway to network

associated with the building where the sensor will be deployed. Then, the

sensor will connect with the USB gateway and send data when the sensor is

powered up, even though it is not yet located in the target building. This

ensures that the sensor is working properly before sending it out into the

field.

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9.1.2 Temperature Sensors

Installation: Thermal grease (heat sink compound) and insulation over the

sensor are very important for achieving accurate readings that are not

distorted by surrounding ambient temperatures.

Accuracy and Calibration: The stated accuracy of the standard Monnit

temperature sensor is +/- 1.8 degrees F at room temperature. We tested

about a dozen temperature sensors at near 140 degrees F and found all of

them to be within 0.5 degrees F of our temperature standard (a +/- 0.18

degree F sensor). We tested a couple sensors at room temperature and all

were within 0.9 degrees F. So, we found accuracy to be better than stated.

We did use Monnit’s calibration feature on some of the sensors, but we do

not currently recommend its use. When using the calibration feature, the

temperature that you enter as the accurate temperature is interpreted as

applying to next reading from the sensor, not the last known reading. So,

your calibration temperature environment needs to be stable. In addition,

we observed strange temperature reading behavior (substantial inaccuracy)

one hour after calibrating four sensors. No explanation has been received

from Monnit for the errant behavior. We chose to undo our calibration on

those sensors.

9.1.3 Pulse Counter Sensor (last item applies to Dry Contact Sensor as well)

Heartbeat Accuracy: For our sensors, we were interested in the pulse rate of

the sensor, i.e. the number of pulses received per unit time. Monnit sensors

report values at a user-specified interval, known as a “heartbeat” interval.

However, the heartbeat timing accuracy is +/- 3%. We eliminated this error

by using the accurate timestamp values that are associated with each

reading to calculate the accurate time interval duration.

How Transmission Problems affect Counts: If a sensor transmission fails to

reach the gateway, the pulse count is not reset to zero, and the next pulse

count will be double its normal value. If the sensor transmissions fail enough

times and the sensor goes into “link” mode (the mode where it tries to find a

suitable gateway to talk to), a 0 pulse count will be transmitted for the next

reading. We made attempts to account for these nuances in our software.

Electrical Noise Issues: We are currently experiencing intermittent and

inaccurate readings from 1 Pulse Count sensor and 2 Dry Contact Sensors

that are mounted near the burners on the Glacier View boilers. We suspect

these issues are related to electrical noise in the sensor environment, but we

are still in the process of resolving the issues. At a minimum, it appears that

43

the Monnit sensors need to be mounted multiple feet away from large

magnetic interference sources such as motors. Other interference

suppression strategies may also be required such as the use of twisted pair

cable, cable shielding, and perhaps a low-pass RC filter.

9.1.4 Occupancy Sensor

No Motion Events: The occupancy sensor sends a transmission marking

accurately the time when motion is detected. However, when motion

ceases, it is not reported until the next heartbeat transmission. Our

occupancy sensors are set to report every 10 minutes, so at worst case, the

reporting of no motion is delayed by 10 minutes. For occupancy sensors

manufactured after July 11, 2013, a mode can be selected that will cause No

Motion times to be reported with little delay.

9.1.5 Lux Light Level Sensor

Accuracy: The sensing element in this sensor has +/- 30% accuracy. If that

level of accuracy is insufficient, the calibrate feature for the sensor should be

used. Remember that the calibration procedure requires a constant light

environment before and after the calibration command is sent. Because of

past issues with temperature sensor calibration, we recommend observing

sensor values for accuracy at least two hours after calibration.

9.1.6 Repeaters

Monnit sells a signal repeater that allows sensors too far from the sensor gateway to

have their signal repeated back to the gateway. We are using two repeaters at the

Chugach Manor facility—one for the natural gas meter sensor and one for the three

sensors measuring snowmelt parameters, which are located in the 1st floor

mechanical room on the West side of the building.

Multiple Repeater Hops: For repeaters manufactured after July 11, 2013,

sensors can utilize more than one repeater hop to reach the sensor gateway.

9.2 Cradlepoint Cellular Router

The Cradlepoint MBR95 cellular router ($120) was used to provide Internet access from

the GCI wireless network for the Chugach Manor and Glacier View facilities. An

upcoming release of the Monnit GSM Sensor Gateway will allow the future elimination

of the cellular router as that function will be built directly into the Monnit gateway.

Cellular Data Modem: The Cradlepoint router requires the of a USB cellular

data modem to actually communicate with the wireless carrier. For this

44

project, we used the Huawei E220 modem, as we found that modem to be

economical ($30) and it successfully connected with the GCI wireless

network.

Configuration Issues: In order to get the Cradlepoint MBR95 / Huawei E220

combination to connect to the GCI wireless network, we learned that two

configuration settings in the Cradlepoint were required. Specifically, “Force

NAT”, available with the “Advanced Mode” settings must be checked. See

Figure 22. Also, the “Access Point Name (APN)” setting must be set to

“web.gci”. See Figure 23.

Figure 22: The required "Force NAT" setting for the Cradlepoint Router on the GCI wireless network.

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Figure 23: The required "Access Point Name (APN)" setting for the Cradlepoint router connecting to the GCI network.

9.3 Ultrasonic Flow Meter, model TUF-2000M

Transit Time versus Doppler: This meter is a “transit time” ultrasonic flow meter

and it will work with clean fluids such as water or glycol solutions. Ultrasonic

flow meters using the Doppler method will not work with clean fluids.

Installation Issues: Cleaning the pipe with sand paper and then rubbing alcohol

improves the signal strength of the ultrasonic transducers. Then, use a layer of

ultrasonic couplant between the sensor and the pipe. Dow Corning 111 valve

lubricant and sealant works well as a coupling agent.

Low Flow Measurement: For applications where low velocity flow needs to be

measured (less than 0.4 feet/second flow velocities), it is important to do a one-

time “zeroing” procedure. Shut off the flow and use Menu 42 to zero the meter.

Pulse Output: The “OCT” (Open Collector Transistor) terminals are used to

provide a pulse output to the Monnit pulse counter. The units and amount

associated with each pulse are set up on Menus 31 – 33. The OCT output is

assigned to produce flow pulses for positive flow values on Menu 78 by selecting

the choice “POS Int Pulse”. The meter can also be configured to produce a 4-20

mA output to indicate flow using Menus 55 – 59.

ahfc building monitoring system project

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