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HVAC Opportunities Mechanical Systems for a Better Climate Ari - - PowerPoint PPT Presentation

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HVAC Opportunities Mechanical Systems for a Better Climate Ari Spiegel, P.Eng., Energy Engineer Nov 19, 2019 Introduction to your Presenter Ari Spiegels experience includes: performing energy audits identifying saving

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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

  • ptimizing 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

1

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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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10 20 30 40 50 60 70 80

Million tonnes CO2e

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

  • Target

BC has a goal to reduce carbon emissions by 40% (baseline 2007) by 2030

  • Solutions

1. 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

2

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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

  • ver 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 Output Input 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

3

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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

4

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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
  • utdoor

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?

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Q & A

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HEATING SYSTEMS

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Boiler Plant Systems

Useful Heat Air Flue Gas Fuel

100 x Energy Fuel Energy Useful Efficiency Boiler 

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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 Boilers

Mid-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

8 5 8 6 8 7 8 8 8 9 9 0 9 1 9 2 9 3 9 4 9 5 9 6 9 7 9 8 9 9 1 0 0 6 0 8 0 1 0 0 1 2 0 1 4 0 1 6 0 1 8 0 R e tu rn W a te r T e m p , F % Efficiency 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

50 Source: Laars Heating Systems

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Hydronic Circuit

Primary only

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Hydronic Circuit

Primary - 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

  • f 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 kWh 100 kWh 100% Electric Heat 8.5 GJ 10 GJ 85% Hi-Eff Natural Gas 15% in flue 10 GJ 10 + 6 = 16 GJ Gas fired Heat Pump

6 GJ from outdoor air

COP = 1.6

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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 Pump

Remote 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
  • f 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

Power required

Higher temperature Lower temperature

Condenser Evaporator

F F O O C OC O 50 40 30 20 10 10 20 30 40 50 120 100 80 20 20 40 60 60 40 50 40 30 20 10 10 20 30 40 50 120 100 80 20 20 40 60 60 40 F F O O C OC O

Heat extracted from inside the building Heat discharged outside the building

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Power Required to Move Heat

Cooling Effect = 1 Ton ≈ 3.6 kW Heat = 4.8 kW

Reference: 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 System

Upgrade

  • 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

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COMPARISON

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Energy Cost Comparison Based on Energy INPUT

Excludes end use efficiency

81 0.02 0.04 0.06 0.08 0.1 0.12 0.14 5 10 15 20 25 30 35 40 Natural Gas Propane Electricity $/GJ Energy Carbon Tax

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INPUT vs OUTPUT Cost of Energy

Price At Meter Price of Useful Heat Output Conversion 13 ¢/kWh 13 ¢/kWh 100% Electric Heat 4.2 ¢/ekWh 10 $/GJ (3.6 ¢/kWh) 85% Hi-Eff Natural Gas 15% in flue 2.3 ¢/kWh 7 ¢/kWh 2+1 = 3 kWh Ground Source Heat Pump

2 kWh from ground

COP = 3

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Energy Cost Comparison Based

  • n Energy OUTPUT

Includes end use efficiency

83 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 10 20 30 40 50 60 Natural Gas Propane Electricity - High Demand Electricity - Low Demand $/kWh $/GJ Cost Carbon Tax Efficiency

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Emissions Comparison

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  • 50

100 150 200 250 Electricity Natural Gas Propane

Emissions Tonnes/GWh

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Wrap Up

5

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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

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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