Air-Source Heat Pump Technology for Heating and Cooling www.hinghamnetzero.org Support a Climate Action Plan For Hingham Welcome to Hingham Net Zero • Hingham Net Zero is a new community group that has been formed to: 1. Raise awareness of the need for aggressive climate action. 2. Support the town's projects to cut emissions. 3. Lend grassroots impetus to community efforts to achieve net zero carbon emissions no later than 2050. 4. Be a clearinghouse for expertise and personalized coaching for people interested in strategies for lowering carbon footprint. • Other towns, such as Concord and Belmont, are moving aggressively to develop and implement action plans to combat climate change. • The Selectmen have recently commissioned a task force under the direction of the Town Administrator to move Hingham toward a climate action plan, building on the work of the Energy Action Committee. • Hingham Net Zero supports and will participate in the new task force. • Hingham Net Zero has over 100 members and is fortunate to have the experience and guidance of former selectwoman Laura Burns. • Join us! Caveats and Disclaimers • I am a homeowner – not a professional HVAC guy or energy efficiency expert. • If you are contemplating a new heating system, you may want to start with a free energy audit: • If you live in Hingham: call Energy New England (ENE Conserve) - 888-772-4242 • For towns without a municipal electric company, call MASSAVE – 866-527-7283 • The staff of these outfits are well-trained, experienced and knowledgeable. • They will give you options/advice tailored to your house and finances. • Heat pumps may be your best solution. Get expert unbiased advice! • Don’t forget simple stuff – insulating, sealing air leaks, LED light bulbs, etc. What Are Air Source Heat Pumps? • Electric-powered compressors efficiently use properties of very cold gas refrigerant under varying pressures to generate either heat or cold. • Works like air conditioning compressor. • In heat mode, the process reverses to warm air. • Heat pumps are typically located outside. • Air exchangers (“mini-splits”) inside the house blow air across refrigerant-filled piping for heating or cooling rooms. • Each exchanger operated by its own remote control – great flexibility. • Each room is separate “zone” served by exchanger for heating or air conditioning. • Major advances in technology like Mitsubishi “Hyper Heat Pump” enable reliable heating in New England winters (tested to 13 degrees below zero). A Picture is Worth…(courtesy of Sustainable Middleboro) What do They Look Like? My 36,000 BTU Hyper Heat Pump: What Do They Look Like? My 24,000 BTU Hyper heat Pump: Wall Mount Air Exchanger – Living Room Floor Mount Air Exchanger - Kitchen Ceiling Vents Also Available Enclosures for refrigerant lines…side of the house Enclosures for refrigerant lines…rear of house Branch box in basement: provides more “ports” The Problem • Gas-fired, cast-iron steam boiler cracked • Steam was either on or off – one big “zone”. • BoilerMate hot water heater made boiler run in summer – steam rose and heated the house! • Automatic cut-off failed and almost caused fire. • Steam: noisy, dirty, temperamental, wasteful • Dwindling contractor expertise. • Cooling house required multiple window air conditioners. • Inefficient, unsightly, noisy, labor-intensive My Situation… • Old New England farmhouse built in 1880; 1,804 square feet • Two floors, unfinished basement, pull-down stairs to attic • Limited closet space not available for ductwork. • Basement has very low ceiling – no room for ductwork. • Two of eight rooms do not communicate with basement or attic. • Several rooms have unique heating/cooling characteristics (e.g, solar gain) and need to be their own zones. • Fire safety a major concern in old wood frame house • Wanted to take advantage of $5,000 electricity credit for solar panels from Hingham Municipal Light Plant. • Self financing/limited budget Proposed Solutions • Two prominent contractors specified variants of the old standbys: • Two gas-fired furnaces/AC compressors located in basement and attic with air exchangers feeding ducts • Extensive ductwork! • Many large holes in 2nd floor ceilings and 1st floor floors for registers • Kluged solutions for the two isolated rooms (small heat pumps or electric radiant heating). Still would need window air conditioners! • What about my $5,000 credit for electricity? • Bids were $56,500 and $37,353 • Four contractors proposed Mitsubishi air-source heat pump solutions: • Bids were $42,487, $29,790, $22,955, $22,800 The Winning Proposal • Two Mitsubishi “hyper heat” external air-source heat pumps: • For 4 larger rooms on south side of house – 36,000 BTU heat pump • For 3 smaller rooms on north side - 24,000 • Total capacity: 60,000 BTU’s • “Branch box” in basement for optimal routing of refrigerant lines • 4 wall-mount internal air exchangers • 3 floor-mount air exchangers • Coastal Heating and Air Conditioning in Quincy MA submitted winning bid; Casoli Refrigeration was very close second. • Total Final Cost: $22,390 • Time to install: one day! Other Project Components • Demolition – removed all steam piping and cast-iron radiators • Cost: $2,000 for demolition contractor plus rental of dumpster • Later found recycling outfits that will rip it out, cart it away and recycle almost for free. • Installed new “hybrid” air-source heat pump water heater. • Cost: $4,020 • Transition required visits from plumber & electrician and use of temporary portable water heater for several days. • Even adding this $6,020 in additional project costs to the winning proposal, it still beat closest gas-fired bid by almost $9,000! Energy Configurations Before and After • Comparison Period 1: Before Heat Pumps • Gas-fired, cast iron steam boiler, gravity-fed cast iron steam radiators • “Boilermate” water heater using heat from boiler • Multiple window air conditioners • 30 year-old Thermidor dual fuel range with gas cook-top/electric oven • Gas dryer/electric washing machine • Period 2: After Heat Pumps • 2 electric heat pump compressors/6 internal “mini-split” air exchangers • Electric “hybrid” water heater uses primarily electric heat pump technology • Thermidor range (due to replace with electric induction soon!) • Gas dryer/electric washing machine • Cook top and dryer use around 3.75 Therms per month Comparing Gas and Electric Power • Total energy usage/costs are disproportionately driven by heating. • How do I compare a gas system to an electric system? • One Therm of natural gas equals 29.3 kWh’s of electrical energy. • To get electrical kWh equivalent of gas, multiple Therms times 29.3. • Example: • Total Therms used in 2018 : 1,853.0 • For kWh equivalent, multiply by: X 29.3 kWh’s • Result: 54,292.9 kWh’s, or “units” • Enabled analysis of energy used by gas boiler vs. electric heat pumps. Comparison – Before/After Heat Pumps • Period 1: 2018 (Oct. 2017 through Sept. 2018 - pre-heat pump) • Period 2: 2019 (Oct. 2018 through Sept. 2019 - post-heat pump) • Total Energy Used expressed in “units” of kWh’s decreased dramatically in 2019. • 2018 usage was 2.59 times 2019 usage! • 2018: 63,500 units (Most of energy used was gas) • 2019: 24,520 units (Most of energy used was electricity – greener/more efficient) • However, Cost per Unit almost tripled (electricity costs more than an equivalent amount of gas): • 2018 Cost Per Unit: $.0640 • 2019 Cost Per Unit: $.1720 • Despite this, annual operating costs increased by relatively small amount – only $152.80 – a 3.76% increase. Comparison – Before/After Heat Pumps • Total energy costs: • 2018: $4,064.18 • 2019: $4,216.92 • Increase, 2019 over 2018: $152.80 • % Increase in operating cost: 3.76% • Electric heat pumps also cool and replaced window AC. • Most of the energy used during both periods was for heating. • Average monthly temperature analysis showed the two periods were almost exactly comparable. • Winter temps of the 2 comparison periods entailed equal heat loads. Comparison – Before/After Heat Pumps • Reduced natural gas consumption from 1,853 Therms in 2018 to 45 Therms in 2019 – a reduction of 98%! • Solar panels produced 40% of all electricity used, further reducing carbon footprint. • Too many variables at play to calculate valid “Return on Investment” (ROI) or “payback period” applicable to others. • However: lower cost of heat pump system compared to gas means electric wins in overall $’s. • $9,000 in project savings spread over 30 years = $300/year – almost 2X $152.80/YR increased annual operating costs.) • Alternative Energy Credits (AEC’s) for heat pumps further shift cost picture to favor electrical HVAC solution. Impact on Carbon Footprint • I used the House tab for carbon footprint calculator at this link: https://www.carbonfootprint.com/calculator.aspx • Entered “one person” to isolate house undiluted by occupancy. • For comparison periods 2018 and 2019, entered the total electricity (in kWh’s) and natural gas (in Therms) used each period. • RESULTS: * • 2018: (Pre-heat pumps) 12.45 Metric tons of CO2e** • 2019: (Post-heat pumps) 6.44 Metric tons of CO2e – almost 50% lower! *This is not counting solar panels **Carbon dioxide equivalent (CO2e) “Carbon dioxide equivalent” or “CO2e” is a term for describing different greenhouse gases in a common unit. For any quantity and type of greenhouse gas, CO2e signifies the amount of CO2 which would have the equivalent global warming impact. Performance and Satisfaction: Positives • Hingham Municipal Light Plant electricity is greener than natural gas and will get greener as HMLP makes further progress in renewable sourcing. • Air exchangers make each room a separate zone. Heat, cool or dehumidify the air with room-specific flexibility. • Remote control for each unit provides flexibility in setting mode (heat, cool, dehumidify, circulate), temperature, fan strength and direction of air flow. • You can program each unit with optimal settings for night, day etc. • Units direct air flow optimally. • “Gentle heat” – it’s more comfortable. Performance and Satisfaction: Positives • Air exchanger intake filters trap dust and are treated with an antibacterial agent – the air you breathe is cleaner.