proposal for scc opus ii

Surrey County Council – Opus II

Proposal for a

Improvements in energy performance

At

Surrey County Council

Opus II, Leatherhead

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To:

Surrey County Council Project Ref: Q003072/DBCounty Hall Date- 12/10/2009Penrhyn Rd Project:- Opus IIKingston upon Thames,SurreyKT1 2DN

Dear Keith,

UNDER THIS PROPOSAL WE WILL:

Examine and report on:-

The use of the building in general and architecture.The equipment, its function, and integrated behaviours.Human factors.

This will allow us to contrast and compare the current situation with the proposals and select those that achieve the best return on investment.

Yours sincerely,

Kieron RyanEnergy and Control Systems

Schedule of Contents

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The building............................................................................................................................................. 4Architecture.............................................................................................................................................. 4Usage....................................................................................................................................................... 4

SYSTEMS......................................................................................................................................................... 5Lighting Controls...................................................................................................................................... 5LTHW....................................................................................................................................................... 5Chiller....................................................................................................................................................... 5FCU.......................................................................................................................................................... 6

OBSERVATIONS ON THE DAY............................................................................................................................ 7Integration................................................................................................................................................ 7Human Factors........................................................................................................................................ 8

ENERGY PROPOSAL......................................................................................................................................... 9Airside Systems....................................................................................................................................... 9LTHW System......................................................................................................................................... 9Lighting System....................................................................................................................................... 9Chillers.................................................................................................................................................... 10

PROPOSAL SYNOPSIS..................................................................................................................................... 101. Re-commissioning Costs.................................................................................................................. 10

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Overview.

The building

The building consists of three storeys plus a small basement area for the LTHW plantroom. There is an exterior enclosure containing the chiller and air handling unit.The building was constructed in the late 1980s.

Architecture

Faced with Kingscourt Hanover Multi bricks (or similar) and interior lined with block work to create a cavity for insulation. Windows are small double glassed aluminium framed and have a solar reflective coating representing 40%-50% of the total vertical surface.

The roof is of a tiled and pitched construction with two small a flat areas traversing the apex. the majority of the smaller area is glass whilst the majority of the larger area is flat and has a small atrium.

The Building would have a footprint of 900 sqm per occupied floor (2700sqm total) plus approx 20sqm at basement level. However the 3 rd floor is significantly smaller and is assumed to be half.Total 900+900+450 + 20 = 2270sqm approx.

The geography of the building is unlikely to be modified. Any expansion of the building Is likely to impact on the car park to the rear. This resource is fully utilized at present.

Usage

The building functions as a general administrative facility. The building is entered via a entrance lobby to the rear adjacent to the car park with significant glass façade and faces West. The entrance doors are security controlled and of the swing type, providing control of the egress of tempered air from the lobby. The lobby is the main thoroughfare containing access to the ground floor rooms and stairs to other levels.The ground floor is divided by interior partitions in to a variety of smaller offices with control of the HVAC systems and lights being defined by the size and occupancy of the space. The first and second floors can be accessed from the staircase located in the lobby. These floors are similar to the ground floors in that they are partitioned in to sub offices with some additional open plan facilities.

The core use the building is unlikely to change, remaining as an administrative office for the district.

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Systems

Lighting Controls

Some space lighting has been modified to incorporate other standalone lighting circuits in order to meet the partitioned space requirement.A smart lighting system is installed (Phillips ECS network controllers in the risers) this appears to be a low cost installation under a separate capital project. There is no method of communicating with the lighting controllers (located In the risers) and therefore our costs to optimise the energy reductions using the existing system is limited.

LTHW

Located in the basement is the low temperature hot water (LTHW) plant, chiller pumps and Motor control centre (MCC).The plant is in good condition and has been well maintained. During the site visit we did not observe an unserviceable equipment.The LTHW system consists of 2 water pressurisation units feeding the LTHW and CHW services. The LTHW circuit consists of 3 off 102 Kw boilers (306Kw total) and 2 pumps 0.75 Kw each (in duty/standby twin head configuration).

A constant temperature circuit provides LTHW to the AHU reheat batteries. However, it is apparent that the pipe work travels vertically up the risers suggesting that this circuit also provides LTHW to the FCU and although this circuit should be scheduled with outside air, this was not apparent as the LTHW supply temperature is running at 60C with an ambient temperature of 16C.It is then left to the down stream controls to draw what is required for local adjustment. A VT circuit is used to provide perimeter heating. We where unable to determine the temperature of the circuit and will assess the control of this circuit as part of the wider impact implied by the failing building control system.

Chiller

The chiller operates under it’s own controls accepting a simple “enable” signal from the Landis and Staefa controller. The chiller then targets a setpoint, nominally 6 C flow and 12C return. There is no load prediction and therefore the system supplies the complete loop with CHW for the entire period of operation.

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FCU

The FCU for the distributed local control for each space. Each unit, and some groups, are controlled by wall mounted Honeywell thermostats (6360 type A or B) having a separate heating and cooling outputs. The units have no network communications and are powered through two contactors located in the risers providing time control in large groups, an occupancy switch on each floor provides an extension period acting on these large groups

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Observations on the day

The space temperature is 25.3C1. The LTHW Flow is 59.6C2

The LTHW Return is 27.3CThe space temperature is high.The flow temperature is unnecessarily high given the ambient temperature.The flow temperature is not scheduled with outside air as this should be lower, we suggest, 60C water is available at 10C and a slope is instigated such that heating ceases above 20C both points should be programmable via a suitable interface.

The difference between LTHW Flow and return (32.3C) suggests that down stream from the boilers, there is a significant demand for heating.

Whilst on the site visit I observed that of the majority of offices are warm and that the 25.3C “space temperature” was not unrealistic throughout the building. Having manual controls on the FCU can cause occupiers to change setpoints from one extreme to the other, that is heating on cooler days and cooling on warmer days, in reality the difference may be trivial but the perception and consequential action has a significant impact on energy consumption especially in summer where cooling is expected. Cooling is more expensive and uses more energy than heating.

Integration.

The single landis and Staefa controller of offers no integration between controllers as no other intelligent controllers are present.The mechanical systems operate as standalone devices operating to achieve a single unrelated parameter i.e. Boilers provide 60C of water, AHU supply tempered air at 21C, chiller provides water at 6C, FCU maintain 25C in the space.The FCU use standalone controls and are not connected to each other or to the main controller.The Chiller plant receives a simple enable signal and provides control of the flow and return water temperatures.The lighting controls are self contained operating on the their own time schedule contained within the lighting controllers, currently inaccessible.

1 Some sensors are located around the building for this purpose because the FCU are standalone and therefore can not contribute.2 Approaching Boiler max flow temp.

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Human Factors

Time schedules programmed as part of the original installation, are unlikely to be energy efficient with regards to current usage.

The accessibility of local setpoints will always cause a degree of disturbance in the plant and the environment because each individual will perceive a different environmental condition.

The manual intervention during the spring and autumn periods causes aberrations in the energy consumption of the building the human factor is vulnerable to over or under compensation of the required conditions.

The inaccessibility of the lighting control system means that the system is not adjusted to meet current and future requirements.

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Energy Proposal

Airside Systems

The AHU provides fresh, tempered air to the FCU. The implication is that it is configured to supply air at some constant temperature. However the AHU is a recirculation type and this means that there will be several distinct possibilities to the function of the AHU contained within the Landis and Staefa controller.

There are several aspects to the AHU that would create immediate energy savings, fan speed control based on the volume of fresh air required, scheduling of the supply temperature with respect to outside air, improvements in the use of the recirculation dampers.Connectivity to an LTHW demand prediction algorithm can be used to further reduce demand across the system.

The FCU thermostat controls should be set and locked to agreed set points, if two FCU serving the same space are referencing different setpoints you will find that one will be achieve 100% cooling and the other 100% heating due to contradicting objectives caused by the internal controls in each.

LTHW System

Many LTHW valves on the FCU are likely to be open, this could be a fault and all FCU heating and cooling valves should be investigated for functionality.

The AHU and FCU are placing an unnecessary load on the LTHW system in order to achieve the programmed supply temperature, the AHU should be re-commissioned and reference values reset as appropriate.

Lighting System

Lighting systems lack an interface and drawings to define the function of the numerous switches around the building.The lighting system should be reviewed and re-commissioned to meet the current requirements, this would create an opportunity to update the system and integrate each space across the lighting and HVAC systems.Many of the lighting tubes, fittings and controls on not as efficient as they could be.Modern light fittings allow for significant energy reductions however this comes at a cost to the business and some degree of inconvenience. Further investigation would be worthwhile and will form part of our discussions with Phillips lighting Solutions.

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Chillers

Two aspects are offered as energy savings. Reconfigure the chiller to implement an predictive algorithm. That is, the flow and return are analysed to determine if the existing status (say, 75% load) is appropriate to meet future demandThis algorithm optimises the run hours by ensuring that compressor 1 operates at maximum efficiency as long as possible before calling compressor 2The time schedule will require reconfiguration and should only provide an enable when outside conditions are not capable of meeting the requirements. That is, the AHU and chiller form part of the intelligence of the building , providing colder fresh air in Winter negates the requirement for the chiller.

Proposal Synopsis Generally the Landis and Staefa controller is adrift from the optimal design parameters.There are to options:-

1. re-commission the existing controls to meet existing requirements2. Replace the existing controls

1. Re-commissioning CostsRe-commissioning of the existing controls; nominally 3 weeks work

Initial survey to establish detailed scope £X,XXX (3 days)Will be deducted from an order to complete the works.

Re-commissioning of equipment £XX,000 2 weeksI have included a nominal sum to include the lighting which is subject to further detailed review with Phillips to define exactly what is achievable

If we where to consider our remote monitoring services:-

Lighting times, Lighting groups, chiller setpoints, AHU setpoints, LTHW setpoints and time schedules etc are likely to be incorrectly set to achieve the current functionality required of the building because access to the lighting and controls is hampered by a lack of information from the original installation.Fore Example; the need to manually turn off the boilers in spring and autumn in order to limit the LTHW temperature.

Documentation on the original installation configuration and user manuals do not support the current installation in full due to continuous site development to the system, input device failure is a possibility and design setpoint retention is unlikely to meet the current use.

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This is supported by high internal space temperatures, all boilers functioning at their internal setpoint of 60C, pumps and fans at full speed, a lack of access to time schedules (allowing for automated on/off controls).

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proposal for scc opus ii

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