4 Bedroom Energy Efficient Passive Home

  • 4 Bedroom Energy Efficient Passive Home

PROJECT DESCRIPTION & SCOPE

The clients were looking for an architect with a track record of very energy efficient designs.   They wanted to build a 4 bedroom single family, very low energy house with a traditional exterior, a conservatory, and informal interior spaces with “craftsman style” accents; all the while keeping the construction budget under control.

The clients owned a unique property overlooking protected tidal marshes on the New England coast.

Upgrading to a full passive house and Net Zero where initially just on their wish list. The clients decided on upgrading to a true passive house & Net Zero near the end of the design phase, after an seeing my energy performance & long term cost savings analysis. A Passivehouse Mechanical engineer was involved in designing a suitable low energy HVAC and energy recovery system.

A comparison between SIPS and stick built construction methods, during the bidding phase, showed that the stick built option was the greener and less expensive of the two choices. Ultimately upgrading to a passivehouse raised the construction cost by just 8%, and reduced the annual energy consumption by better than 80%, compared with a conventionally built house.

 

PROJECT SPECS

3,500 SF 4 bedroom Passivehouse with Conservatory

Peak Heating Load

20,700 BTU instead of 110,00 BTU

Annual (projected) Heating:

equal to 97 gallons of oil (4,014 KW) instead of 670 gallons of oil (27,500KW) – 87% less

Back up heating

50,000 BTU gas fireplace

Insulation

Walls R=45.7 (12 .5”) Roof R=49 (12”) Floor R=51 (13.5”)

Window:

Triple-glazed R=7.14 (standard window R=2.5)

Heating/Cooling

One 2-ton Geothermal Heat Pump

Water Heater

Stiebel Elton Heat Pump with tank (3x more efficient than a gas fired Water heater)

Air Tight

<0.6 air changes/hour instead of 8x air changes/hour

Energy Recovery Ventilation

Automatic (86% efficient)

Photovoltaic (Solar) electricity

8.1 KW grid-tied system

Passivehouse features added +/- 8% to the construction cost (conservatory and Solar system excluded)

Energy use comparison is based on a code complying house.