HVAC Opportunities

Mechanical Systems for a

Better Climate

Ari Spiegel, P.Eng., Energy Engineer

Nov 19, 2019

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Introduction to your Presenter

Ari Spiegel’s experience includes:

• performing energy audits

• identifying saving opportunities

• performing energy analysis and saving

calculations

He is involved in BC Hydro Continuous Optimization

program which focuses on retro-commissioning of

building mechanical systems.

He has experience with building automation and

optimizing building control systems to improve

performance = quantified energy saving results.

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Who We Are

From design to implementation, we provide

energy management, electrical and mechanical

engineering, utility monitoring and sustainability

consulting to help our clients create a greener,

more energy efficient world.

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Desired Outcomes

• better understand typical mechanical

systems in multi-unit residential buildings

(MURB)

• introduction to greener opportunities

• inspire you to take on new challenges

• motivate you to reduce energy and GHG

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Today’s Agenda• Sustainability in BC

• Energy basics

• Mechanical Systems Overview

• Energy and Carbon Saving

Opportunities

– Fan systems

– Heating

– Domestic hot water

– Cooling

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Sustainability in BC

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GHG Emissions in BC

Source: Environmental Reporting BC. 2018. Trends in Greenhouse Gas Emissions in B.C. (1990-2016). State of Environment

Reporting, Ministry of Environment and Climate Change Strategy, British Columbia, Canada.

http://www.env.gov.bc.ca/soe/indicators/sustainability/ghg-emissions.html

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CleanBC Announcement

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CleanBC’s Targets:

2012 – 6% below 2007 emissions

2030 – 40%

2040 – 60%

2050 – 80%

Canada’s Targets:

2012 – 6% below 1990 (Kyoto)

2030 – 30% below 2005 (Paris)

BC GHG Emission Plans and Targets

Kyoto

Protocol

1995 BC

Plan

2000

Plan 2008 Plan

2016

Plan

UNFCCC

1992

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CleanBC - Buildings

Source: https://news.gov.bc.ca/files/CleanBC_HighlightsReport_120318.pdf

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Available Incentives

Source: https://betterbuildingsbc.ca/incentives/social-housing-retrofit-support-program/

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Low Carbon Electrification (LCE)Definition

The reduction of greenhouse gas

emissions, by using clean electricity

instead of other forms of energy such as

gasoline, natural gas and diesel.

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High Carbon Grid Example: SaskPower

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Clean electricity

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Greenhouse Gas Emission Goals

• TargetBC has a goal to reduce carbon emissions by 40% (baseline

2007) by 2030

• Solutions1. Upgrade to high efficiency fuel systems

2. Improved building envelope

3. Switch from fossil fuel power to low carbon electricity

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In BC - Efficient Electrification with Heat Pumps

• HP’s play a huge role in meeting carbon targets

• Efficient electrification

– It’s not about resistance heating installations!

• Grid capacity constraints

• End user energy cost

• Typical Efficiency

– 2 to 4x as efficient as base board electric

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Energy Basics

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Basic Electricity Terms

• Power

– When voltage and current work together to do

something useful – such as turn a motor or light a

lamp. Units are watts (W)

• Demand

– Peak (maximum) rate of electricity usage, within

a billing period, which is drawn by a customer

over any 15 or 30 minute interval.

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Power & Energy

Power: Watts = Volts x Amps x Power Factor

Kilowatts = Watt/1000

Energy: Energy = Power x Time

kWh = kW x hours

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Demand Example

Amount of water =

Energy

High Demand

(short fill time)

Low Demand

(long fill time)

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BC Hydro Rates - 2019

• Residential

• Medium General Service

• Large General

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Thermal Energy Units and Rates• Unit of thermal energy is a Joule (J)

– Typically use MJ or GJ

• 1 Joule per second = 1 Watt

• 1 kWh = 3.6 MJ (0.0036 GJ)

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What is Efficiency?

Useful OutputInput

Efficiency = × 100%

Electric heat

Atmospheric Boiler

Condensing Boiler

Heat Pump

100%

50-80%

80-95%

300-500%

Elec. – Heat

Gas – Heat

Gas – Heat

Elec. – Heat / Cool

Device Efficiency Input – Output

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Mechanical Systems Overview

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Systems Overview

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Ventilation -Make-up Air Unit (MAU)

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Heating –Hydronic Heating

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Domestic Hot Water

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Heating - Terminal Units

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Cooling Systems

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Air Source Heat Pump

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Energy and Carbon Reduction Opportunities

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VENTILATION SYSTEMS

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Standard Efficiency MAU

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High Efficiency MAU• Condensing gas fired ventilation

• 12% increase in efficiency compared to

conventional

Opportunity #1

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High Efficiency Gas Burner

• Two heat exchangers

– Primary (conventional)

– Secondary (condensing)

• Up to 95% efficiency

• Condensate management

(neutralize)

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MUA with Heat Pump

Opportunity #2

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Air Source HP Operational Considerations – Air Temp

Rated to

-20°C

outdoor

Performance drops with a

decrease in outdoor air

temperature

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Installation Considerations –Air Temp

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Before After

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• Natural Gas Savings of 400 GJ

• Electrical increase of 28,400 kWh

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Cost Breakdown Like-for-like

Replacement

Electrification

Option

Mobilization $1,500 $1,500

Demolition $800 $800

Equipment $21,700 $24,300

Hoisting $1,400 $1,400

Structural $1,500 $1,500

Ductwork $1,000 $1,000

Emergency Devices $0 $0

Electrical $1,500 $1,500

Controls $800 $2,000

Balancing, Commissioning $750 $750

Other $2,800 $2,800

Sub-Total $33,750 $37,550

Overhead and profit 20% Mech &

Elect $6,800 $7,510

Contingency 5% $1,800 $1,878

Construction Total $42,350 $46,938

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Estimated

Actual 3 Bids: all bids had heat pump RTU $2,000 to $5,000 lower than high efficiency gas fired RTU

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Considerations

• Low fuel prices make fossil

fuels more financially viable

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• Location - low ambient

temperature require natural

gas or direct electric backup

Increasing carbon tax

improves economics

• Higher capital costs

Heat pump technology is

increasingly performing

better at low ambient

temperatures

Policy – building codes

• Is there available electrical

capacity?

Other benefit from an

electrical upgrade?

Q & A

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HEATING SYSTEMS

Boiler Plant Systems

UsefulHeat

Air

Flue Gas

Fuel

100xEnergyFuel

EnergyUsefulEfficiencyBoiler

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Efficiency: Boilers & Furnaces

• Combustion Efficiency– Instantaneous efficiency of burning fuel example 86%

– Represents unburned fuel and/or excess air loss

• Overall Efficiency– Instantaneous efficiency of producing hot water (air), steady

state, example 80%

– Introduces convection & radiation

• Seasonal Efficiency– Over time (heating season) efficiency of producing hot water

(air): 72%

– Incorporates the effect of cycling, stand-by and off cycle losses.

Ref: ASHRAE System and Equipment Handbook, 2000, pg 27.5

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Atmospheric Boilers

• Aka “Natural Draft”

• Thermal efficiency typically 80%

• Seasonal efficiency lower (50-75%) due to:

• Radiative (jacket) losses

• Draft hood continues to draw air through boiler even when it is not firing, cooling it down

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Forced Draft BoilersMid-Efficiency

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• Fan-assisted combustion

• Thermal efficiency of 85%

• Seasonal efficiency is reduced due to post-purge cycle to clear the flue and burner of combustible gases.

• If boiler short-cycles, energy losses via purge cycle can be significant.

Opportunity #3A

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Condensing boilers

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• Similar burner to Forced Draft.

• Flue gas passes through heat exchanger, pre-heating return water as it enters the boiler.

• Requires low return water temperature to achieve condensing and high efficiencies.

• Low return water temperature (<55°C) allows for flue gases to condense and latent heat to be recovered.

Opportunity #3B

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Condensing Requires Low Return Water Temperature

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6 0 8 0 1 0 0 1 2 0 1 4 0 1 6 0 1 8 0

R e tu r n W a te r T e m p , F

% E

ffic

iency 2 5 % F ir in g R a te

5 0 % F ir in g R a te

7 5 % F ir in g R a te

1 0 0 % F ir in g R a te

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Source: Laars Heating Systems

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Hydronic CircuitPrimary only

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Hydronic CircuitPrimary - Secondary

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Air to Water Heat Pump

Opportunity #4A

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Water Source Heat Pump

Opportunity #4B

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Heat Transfer Fundamentals

• Heat pumps do not deliver the same high

temperature as natural gas appliances.

• As a result, larger equipment (like air handling

unit coils) are needed to get the same amount

of heat delivered.

• You can not replace a natural gas boiler with an

electric heat pump without considering the

terminal HVAC equipment.

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Consider temperature

• Coefficient of performance (COP) can change significantly

depending on the supply temperature (condenser temp)

OAT C

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Hydronic Baseboards

Low Temperature vs High Temperature

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Hydronic Coils

• Low Temperature vs High Temperature

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New Technology –Gas fired absoption heat pumps (GAHP)

Opportunity #5

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GAHP Refrigeration Cycle

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High Efficiency Supply Options

Energy in Useful Heat

Output

Conversion

100 kWh100 kWh 100%

Electric Heat

8.5 GJ10 GJ 85%

Hi-Eff Natural Gas15% in flue

10 GJ

10 + 6 = 16 GJGas fired Heat Pump

6 GJ from outdoor air

COP = 1.6

Q & A

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DOMESTIC HOT WATER SYSTEMS

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Domestic Hot Water• Electric or gas heater

• Served by a central system

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Domestic Hot Water Heat Pump

• Air to water heat pump

• Ambient indoor air used as

source (can help

dehumidify space installed

within)

• Or split system with

condenser unit outside

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Opportunity #6

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CO2 Heat Pump• Heat from outdoor air

• Environmentally friendly refrigerant

• Split system (air to water)

• Direct exchange (refrigerant line

runs from tank to outdoors)

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Domestic Hot Water Heat PumpRemote Health Care Site, Northern Vancouver Island

• Existing propane

fired DHW heaters

• High fuel transport

costs

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CO2 Heat Pump

Advantages:

• Ability to generate considerably higher leaving water

temperatures (up to 90°C) than conventional heat pumps. Therefore ideal for DHW applications

• Low global warming potential (GWP) CO2 GWP = 1.

R134a GWP = 1500.

• Lower health and safety risk in the event of a

refrigerant leak

• Relatively flat performance (COP) curve over a range

of ambient temperature conditions (maintains

efficiency even at low outdoor temperatures)

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CO2 Heat Pump

Drawbacks:

• Relatively new technology and not yet widely

adopted in the Canadian market (larger in

Europe and Asia)

• Higher operating pressures, requiring more

robust components

• Requires low entering water temperatures to

ensure efficient operation (needs to be loaded)

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Q & A

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COOLING SYSTEMS

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Why is Cooling a Topic?

• Climate Adaptation

• Benefit of Heat Pump system

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Moving Heat … Uphill

Powerrequired

Highertemperature

Lowertemperature

Condenser

Evaporator

FFOO

CO

CO

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FFOO

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Heat extracted from insidethe building

Heat discharged outsidethe building

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Power Required to Move Heat

Cooling Effect = 1 Ton ≈ 3.6 kW

Heat = 4.8 kWReference: GPG 279

Power In = 1.2 kW

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End of Life Chiller Replacement– Case Study

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Overview• The existing chiller and condensing unit were more

than 30 years old and parts were no longer

available

• Chilled water from the chiller is circulated to chilled

water cooling coils in the four air handling units

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Chiller Replacement with Heat Pump SystemUpgrade• The existing chilled water cooling coils in the

four air handling units were removed and

replaced with four refrigerant cooling coils

• The condensing units were selected as heat

pumps to provide supplemental heating in

addition to cooling

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Control View

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Cooling coil

HP for h/c

Cooling coil

replaced with

HP for h/c

Hot water

Heating Valve

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Before After

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Results – Electrical & Fuel

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50% Annual

Gas Savings

Reduction in

Electrical

Savings

COMPARISON

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Energy Cost Comparison Based on Energy INPUTExcludes end use efficiency

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Natural Gas Propane Electricity

$/G

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Energy Carbon Tax

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INPUT vs OUTPUT Cost of Energy

Price At Meter Price of Useful

Heat Output

Conversion

13 ¢/kWh13 ¢/kWh 100%

Electric Heat

4.2 ¢/ekWh10 $/GJ (3.6 ¢/kWh) 85%

Hi-Eff Natural Gas15% in flue

2.3 ¢/kWh7 ¢/kWh

2+1 = 3 kWhGround Source Heat Pump

2 kWh from ground

COP = 3

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Energy Cost Comparison Based on Energy OUTPUTIncludes end use efficiency

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Natural Gas Propane Electricity - High Demand Electricity - Low Demand

$/k

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Cost Carbon Tax Efficiency

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Emissions Comparison

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Electricity Natural Gas Propane

Emissions Tonnes/GWh

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Wrap Up

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Considerations

• Carbon Reduction Focus vs. Operating Cost

Impact

• Climate Change Adaptation needs: do you

want to prepare for cooling?

• What is the life expectancy of your existing

equipment? Look for ways to integrate

upgrades into your capital plan

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Summary of Opportunities

Each system has limitations that need to be considered

when selecting the system type

Opportunity System Technology

1 Ventilation High Efficiency MAU (~95%)

2 Ventilation Heat Pump MAU (~350%)

3A Hydronic Heating Mid Efficiency Boiler (~85%)

3B Hydronic Heating High Efficiency Boiler (~92%)

4A Hydronic Heating Air Source HP (~350%)

4B Hydronic Heating Water Source HP (~450%)

5 Hydronic Heating Gas Fired Heat Pump (~160%)

6 DHW CO2 Heat Pump

Q & A

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Thank you.

Prism Engineering Limited

www.prismengineering.com

Ari Spiegel, P.Eng., Energy Engineer

aris@prismengineering.com

604-298-4858

@Prism_Eng