Passive House

In 2007 Sustainable Energy Ireland (SEI) produced guidelines for the design and construction of Passive House Dwellings in Ireland. It defined a passive house as “an energy-efficient building with year round comfort and good indoor environmental conditions without the use of significant active space heating or cooling systems. The space heat requirement is reduced by means of passive measures to the point at which there is no longer any need for a conventional heating system. The air supply system essentially suffices to distribute the remaining heat requirement.”

“A passive house provides a very high level of thermal comfort and provision of whole-house even temperature. The concept is based on minimising heat losses and maximising heat gains, thus enabling the use of simple building services”. See here for a simple graphic model. See video for a quick explanation. This video outlines why a Passive House is desirable. In fact, the only essential energy technology required in a Passive house is the heat recovery ventilation system.

The appearance of a Passive house does not need to differ from a conventional house and living in it does not require any lifestyle changes. Passive houses are naturally well lit due to large glazed areas designed to optimise solar gains, as well as healthy buildings in which to live and work due to fresh air supply through the controlled ventilation system. The Passivhaus Standard is a construction standard developed by the Passivhaus Institut in Germany. See The standard can be met using a variety of design strategies, construction methods and technologies and is applicable to any building type.”

“The Passivhaus Standard is a specific construction standard for buildings which provide for good comfort conditions during winter and summer, without traditional space heating/cooling systems. Typically this includes optimised insulation levels with minimal thermal bridges, very low air-leakage through the building, utilisation of passive solar and internal gains and good indoor air quality maintained by a mechanical ventilation system with highly efficient heat recovery”.

In April 2016 ProAir Systems received Passive House accreditation for one of its products ProAir 600PLI.

There is a big difference between building, say a BER A Rated house and a Passive house. The standard BER rating is based on plans provided. No tests are carried out. To achieve Passive house certification, work must be checked and completed to a predetermined standard during the course of the build and at the end.

Having low energy usage for heating means that Passive house owners will be largely free of concerns re fuel poverty, reliance on fossil fuels and excess CO2 emissions. The energy requirement of a house fitted with an MVHR system will be significantly less than the naturally ventilated house. As a follow on the CO2 emissions will be lower.

Passivehouseplans, a team of experienced architects and engineers, has calculated heating costs and probable payback period for houses built to Passive House standard in Ireland. The following summarises their findings

House Type Annual Cost Increase in Fuel Payback
Estimated Cost Saving after 25 years EUR
173m2 Block
2 Storey 4 Bed
8% 9 112, 617
5% 10 64,927
178m2 Block
1 1/2 Storey 3 Bed
8% 9 113,452
5% 9 66,470
212m2 Block
2 Storey 5 Bed
8% 10 111,689
5% 12 70,008
228m2 Block
2 Storey 5 Bed
8% 7 165,836
5% 8 99,772

If alternative sustainable energy sources are used along with Passive design a house could be ‘energy plus’. One of the corner stones of building a Passive house is that time and effort are invested in building to a very high standard before investing in alternative heating systems. In Ireland to date emphasis has been put on alternative heating systems trying to achieve ‘low energy’ status without getting the actual building ‘right’. For the future it must be a case of ‘fabric before technology’.

Within a few years Ireland will have to start delivering carbon neutral buildings. This is part of the target set by Department of the Environment. Passive houses are therefore the only way forward. Heat recovery ventilation is a key component of all Passive houses.