HVAC Opportunities Mechanical Systems for a Better Climate Ari Spiegel, P.Eng., Energy Engineer Nov 19, 2019
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. 2
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. 3
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 4
Today’s Agenda • Sustainability in BC • Energy basics • Mechanical Systems Overview • Energy and Carbon Saving Opportunities – Fan systems – Heating – Domestic hot water – Cooling 5
1 Sustainability in BC 6
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 7
CleanBC Announcement 8
BC GHG Emission Plans and Targets 80 2000 1995 BC 2008 Plan Plan Plan 70 2016 Plan Kyoto 60 Protocol UNFCCC 1992 50 Million tonnes CO2e 40 30 CleanBC’s Targets: 20 2012 – 6% below 2007 emissions Canada’s Targets: 2030 – 40% 2012 – 6% below 1990 (Kyoto) 2040 – 60% 10 2030 – 30% below 2005 (Paris) 2050 – 80% 0 9
CleanBC - Buildings 10 Source: https://news.gov.bc.ca/files/CleanBC_HighlightsReport_120318.pdf
Available Incentives 11 Source: https://betterbuildingsbc.ca/incentives/social-housing-retrofit-support-program/
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. 12
High Carbon Grid Example: SaskPower 13
Clean electricity 14
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 15
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 16
2 Energy Basics 17
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. 18
Power & Energy Power: Watts = Volts x Amps x Power Factor Kilowatts = Watt/1000 Energy: Energy = Power x Time kWh = kW x hours 19
Demand Example High Demand (short fill time) Low Demand (long fill time) Amount of water = Energy 20
BC Hydro Rates - 2019 • Residential • Medium General Service • Large General 21
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) 22 22
What is Efficiency? Useful Output Efficiency = × 100% Input Device Efficiency Input – Output Electric heat 100% Elec. – Heat Atmospheric Boiler 50-80% Gas – Heat Condensing Boiler 80-95% Gas – Heat Heat Pump 300-500% Elec. – Heat / Cool
3 Mechanical Systems Overview 24
Systems Overview 25
Ventilation - Make-up Air Unit (MAU) 26
Heating – Hydronic Heating 27
Domestic Hot Water 28
Heating - Terminal Units 29
Cooling Systems 30
Air Source Heat Pump 31
4 Energy and Carbon Reduction Opportunities 32
VENTILATION SYSTEMS
Standard Efficiency MAU 34
High Efficiency MAU • Condensing gas fired ventilation • 12% increase in efficiency compared to conventional Opportunity #1 35
High Efficiency Gas Burner • Two heat exchangers – Primary (conventional) – Secondary (condensing) • Up to 95% efficiency • Condensate management (neutralize) 36
MUA with Heat Pump Opportunity #2 37 37
Air Source HP Operational Considerations – Air Temp Performance drops with a decrease in outdoor air temperature Rated to -20 ° C outdoor 38
Installation Considerations – Air Temp 39 39
Before After • Natural Gas Savings of 400 GJ • Electrical increase of 28,400 kWh 40 40
Cost Breakdown Estimated Like-for-like Electrification Replacement 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 Actual 3 Bids: all bids had heat pump RTU $2,000 to $5,000 lower than high efficiency gas fired RTU 41 41
Considerations • Low fuel prices make fossil Increasing carbon tax fuels more financially viable improves economics • Location - low ambient Heat pump technology is temperature require natural increasingly performing gas or direct electric backup better at low ambient temperatures • Higher capital costs Policy – building codes • Is there available electrical Other benefit from an capacity? electrical upgrade? 42 42
Q & A 43
HEATING SYSTEMS
Boiler Plant Systems Useful Energy Boiler Efficiency x 100 Fuel Energy Flue Gas Useful Heat Fuel Air
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 46
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 47 47
Forced Draft Boilers Mid-Efficiency • 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 48 48
Condensing boilers • 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 49 49
Condensing Requires Low Return Water Temperature 1 0 0 9 9 9 8 9 7 9 6 9 5 9 4 % Efficiency 2 5 % F ir in g R a te 9 3 5 0 % F ir in g R a te 7 5 % F ir in g R a te 9 2 1 0 0 % F ir in g R a te 9 1 9 0 8 9 8 8 8 7 8 6 8 5 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 Source: Laars Heating Systems 50 50
Hydronic Circuit Primary only 51 51
Hydronic Circuit Primary - Secondary 52 52
Air to Water Heat Pump Opportunity #4A 53
Water Source Heat Pump Opportunity #4B 54
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. 55 55
Consider temperature • Coefficient of performance (COP) can change significantly depending on the supply temperature (condenser temp) OAT C 56
Hydronic Baseboards Low Temperature vs High Temperature 57 57
Hydronic Coils • Low Temperature vs High Temperature 58 58
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