The Passive House movement began in the late 1980’s in Europe as a set of voluntary standards to massively reduce the energy requirements of residential and commercial buildings. The initial designs evolved from “superinsulation” designs in North America that were pursued as a result of the OPEC oil embargoes of the 1970s.
Continuous insulation is a key principle of passive house construction that aims to reduce heat loss and thermal bridging through the building envelope. Green Insulation Group is a Worcester based source of reclaimed, recycled or surplus foam insulation boards that are the mainstays of continuous insulation installations.
A passive house retrofit will (almost) never achieve the same energy savings as new passive house construction, however you can achieve 75 – 90% energy savings using the EnerPHit certification standards (according to Passipedia, an amazing passive house resource).
Overview of the Passive House retrofit process:
- Improved thermal insulation (continuous insulation)
- Reduction of thermal bridges (continuous insulation)
- Considerably improved airtightness (blower door test ACH 1.0 or less, new construction < 0.6)
- Use of high-quality windows (triple-glazed & passive house certified = R12)
- Ventilation with highly efficient heat recovery (heat exchange ventilation)
- Efficient heat generation (electric heat pump)
- Use of renewable energy sources (typically solar panels)
As you can see, this is an integrated system of efficiency improvements that must all be implemented for greatest energy savings. However, doing all of these at once during a retrofit is not always practical. Keep in mind though that very airtight structures must be coupled to improved ventilation to avoid air quality issues and moisture problems.
Here are some more passive house retrofit resources: