by Paul Kando – Midcoast Green Collaborative
The four-story structure on Portland’s Cumberland Avenue contains a three-car garage, two rental apartments and a fabulous two-story master apartment with panoramic views of the city from the Atlantic to Back Bay. For all that it does not strike the passerby as out of the ordinary. That’s because it was designed to fit in with its Munjoy Hill neighbors. Yet as houses go it is anything but. For one thing, it generates 9,600 kWh of its own electricity annually and most of the hot water needed by its seven residents. For another, the house is super energy efficient. It has no air leaks and is super-insulated.
There is heat recovery ventilation (HRV) throughout, which continually removes stale air, transferring most of its heat content to the incoming fresh air. Hot water is supplied by a solar array of 90-evacuated-tubes on the roof.
All heating and cooling is provided by air source heat pumps, which work somewhat like your refrigerator, transferring heat by pumping a hot fluid from one place to another. Heat pumps are very efficient and therefore economical to operate. They have high coefficients of performance, as high as 3, in other words they can be up to 300% efficient in their use of electricity.
For all this, including the elevator serving the upstairs master apartment, owner Paul Ledman expects to pay only about $60 per month for electricity for their two story master apartment, including the cost of heating and cooling. And he expects the initial investment in the building’s energy features to pay for themselves in five to six years. After that, Paul says, we are saving. The tenants in the two rental apartments pay for their own utilities. However they get most of their hot water free and benefit from all the building’s energy-economies. Everybody wins.
Net Zero Energy. Efficient. Economical. Financed by rental income and energy savings. All without sacrificing year round comfort and lifestyle. A house of the future indeed.