Keep What You Got
Before the widespread use of mechanical heating and air conditioning, all houses were passive houses. New England saltboxes, adobe houses and igloos were methods that communities would use to make their built environments more comfortable with little or no heroic mechanical intervention.
The advent of air conditioning and gas heating, coupled with the traditionally low cost of energy, made it rare for home builders to concern themselves with natural environmental factors for maintaining a comfortable home.
The climbing cost of energy production, from both a monetary and global perspective, suggests a different approach, favoring a re-engagement with passive house strategies.
Originally a German invention, the goal of PassiveHaus was dramatically lower energy use (using the metric of kilo-watt hour/ square meter, or BTU/ square foot) through several important principles:
An increase in insulation values at the building envelope to include walls, roofs, floors and high performance windows and doors.
Elimination of air ‘leaks’ in the envelope.
A strict accounting for fresh air introduced and stale air exhausted with temperature and humidity gleaned from the exiting air to temper the incoming, fresh air.
Elimination of ‘thermal bridging’; elements of construction that compromise the integrity of the insulation.
Utilization of Passive Solar techniques, using thermal masses within the home to store and gradually release radiant energy from the sun.
and, perhaps most importantly,
Verification of all of the above.
The German model instituted a single standard for all construction that pursued certification as a Passive House.
The single model that was ideally suited for northern Europe was less responsive to the myriad climate types found throughout the United States; PHIUS was developed to address this need.
“Keep what your got”, might be a short-hand version for the benefits of Passive House design. The home owner has paid for the energy to heat, cool and humidify/dehumidify the house; there is no benefit to let them leak them from the house through inadequate insulation or gaps in the walls. A modest increase in construction costs, in the 3-5% range, may result in and energy reduction of 85% compared to standard home construction.
Building and Energy codes are steadily increasing tightening the building envelope and increasing the insulation values - but this still represents the worst envelope you are allowed to build. Passive House design leapfrogs to the front of energy conscious design with high standards and field verifiable results.
Peter VanderPoel is a Certified Passive House Consultant