Dear Readers,
This post was written by our friends at Electrify My Home (“EMH”). We were eager to share it here because it represents the challenges and opportunities homeowners face in pursuit of comfort and sustainability. Read on, and we welcome your responses in the comments!
– Sam & Gautam, Greenwork Founders
Project at a Glance
- Type: Home electrification
- Location: Berkeley, CA
- Components: Heat pump HVAC, heat pump water heater, insulation, duct work
- Contractor: Electrify My Home
About the Client
Our client is an employee of the City of Berkeley and a member of the Berkeley Electrification Group. More than most homeowners, our client and her family are aware of how increasing atmospheric concentrations of CO2 are affecting the climate and the benefits the family and environment would realize if the home was converted to 100% electric.
During the Camp Fire… we were instructed to stay indoors with windows closed… I was [not] going to turn on my oven… But I still needed hot water and was stuck with that gas tank in my kitchen.
Our client contacted us to replace the old natural gas furnace with a modern, high-efficiency heat pump unit, and make other changes that qualified for rebates while also moving the home toward becoming 100% electric.
About the House
- Year Built: 1948
- Size: 1042 sq ft
- Existing HVAC: Equipped with a 60,000 BTU 90% efficient central forced-air natural gas-burning furnace but no A/C and no solution to filtering smoke from wildfires. Ducts were in poor condition and contaminated.
- Existing Water Heating: A 1990, 40-gallon Montgomery Ward brand gas water heater located in the kitchen closet that was beginning to fail. There was evidence of significant “spillage,” which is a term used to describe combustion gasses spilling into the home instead of properly venting out the chimney.
Project Goals
The customer’s goal was complete decarbonization. In order to achieve this, a conversion of the existing appliances was a natural first step. Other issues included very poor comfort and uneven temperatures throughout the house. In fact, plug-in space heaters were used around the house in lieu of the central furnace which hadn’t been used in years because of its poor performance. This led to high energy bills, inefficiency, and continued comfort complaints.
The customer was also focused on reducing their loads to the point where they could easily be offset with solar panels. This can only be effectively achieved through electrification and smart system planning.
Project Scope
Envelope
To cut down on thermal losses, blown-in cellulose insulation was installed to an effective R-value of R-44.
New Duct System
New R-8 ductwork was designed from scratch using a Manual D load calculation and room-by-room air flows. Mechanical elbows, short tight runs, a larger return air duct, and correct registers were all used to cut down on static pressure leading to a highly efficient outcome.
New HVAC System
A right-sized 18,000 BTU Fujitsu inverter heat pump was designed with a Manual J and installed to spec. This is 42,000 BTU less than the existing system! Because of the modulating nature of this system, its capacity range goes as low as 5,400 BTU all the way up to 25,600 BTU in heating mode.
Install Small
Our approach was to “Install Small,” which means reducing heat losses so that we could replace the old gas furnace with something intentionally less powerful. As a result, the home has been comfortable, efficient, convenient, and quiet.
Installing a high-efficiency central “mini split” heat pump allowed more than a two-thirds reduction in the heating capacity of the system — from 60,000 to 18,000 BTU. Heat losses were reduced by replacing the old ducts with new, properly sized, insulated R8 ductwork. Our client now saves a lot of money on their heating bills while having the added bonus of whole-house cooling during the summer months.
This is the load calculation performed for this home. It comes from software (Wrightsoft), and takes into account various building components (e.g. insulation levels, orientation, window types) to determine the optimal system sizing, duct sizing, and airflow. Side-note: in a brand-new cut-in scenario, registers are placed in areas closest to the air handler to cut down on thermal losses and improve static pressure. To save money, the existing registers were utilized.
New Heat Pump Water Heater
A 50-gallon RUUD heat pump water heater was installed to replace the existing gas unit. An added benefit of this unit is the free cooling it now provides to the garage, where the unit was relocated. A mixing valve was also installed to increase tank capacity and provide the customer with the ability to coast their systems through demand response or periods of expensive electricity (e.g., 4–9pm).
Outcome
In our client’s words:
https://www.youtube.com/watch?v=067nWzM1zh8
All-electric homes are safer, healthier and more comfortable than gas-powered homes, and all-electric homes powered by renewable energy have zero greenhouse gas emissions
The air source heat pump is fantastic. It is so quiet, I don’t even know that it’s running.
The heat pump has provided hot water for my family of four (including teenagers who like to take long showers) without a hitch.
About EMH
Electrify My Home (“EMH”) is a transformational home electrification business that is working with the State of California to meet its greenhouse gas emission reduction goals. EMH was selected by California’s $200MM “TECH Clean CA” initiative as the primary trainer guiding HVAC businesses in their transition to offering heat pumps and other energy-saving technologies. Meanwhile, EMH is a “Boots-on-the-ground” organization that is installing advanced heating and cooling systems on a daily basis. EMH is always looking for ambitious and hard-working individuals to join its installation team; contact us today at info@electrifymyhome.com to learn more.
