Sunday, August 4, 2013
EnerPHit Good For Maine
Maine is one of our countries worst offenders when it comes to using oil to heat our buildings. According to the U.S. Energy Information Administration, EIA, "About four-fifths of Maine households use fuel oil as their primary energy source for home heating, a higher share than in any other State." The Northeast Biomass Working Group commissioned an analysis by Futuremetrics showing Maine as the fourth most petroleum state in the country with 70% of buildings heated with oil costing a billion dollars a year in exported spending shown here.
But the Passive House organization, Passivhaus Institut, has created a category for existing buildings called EnerPHit which adjusts the requirements for new building certification to account for the difficulty involved in renovating. Thus the air infiltration requirement for a new Passive House is maximum .6 air changes per hour but the retrofit standard is maximum 1.0. And the requirement for heating energy demand goes from 4.75 kBTU/ft2yr to around 8.
Most of the work to achieve the retrofit standard involves superinsulating the building shell. Replacing the usually energy inefficient windows with Passive House certified triple glazed ones with better thermal bridge free installation details is fairly straightforward compared to tackling the whole shell. Usually a combination of insulation methods is used specific to existing conditions. For instance it may be a good idea to spray foam insulate between studs or rafters or to add another row of studs to create a double wall and fill it with cellulose, etc. Some situations may be easier tackled by placing 8 inches of rigid insulation over the exterior walls and using the existing stud wall as a service cavity.
The important thing is for us to begin the process of eliminating fossil fuel use in this state and EnerPHit provides us with a metric to approach this problem with. PassivhausMaine will be holding an EnerPHit forum this September 27th in the morning at the Portland Public Library.