From Passivhaus to passive hoose?

Towards the end of last year, the Scottish Government announced that they will make subordinate legislation within two years which will introduce new minimum environmental design standards for all new-build housing to meet a Scottish equivalent to the Passivhaus standard.

In one of our Housebuilding Conversations, Alex Rowley MSP spoke passionately about the Private Members' Bill he was seeking to introduce to ensure that all new build housing be designed to improve environmental efficiency, reduce fuel poverty, improve occupational comfort and work towards net zero targets. The Bill process can be a lengthy one, so its effective adoption by the Scottish Government will see the proposed standards fast-tracked with new legislation in force to give effect to the proposed Bill by December 2024. This will be in addition to the new building regulations on energy standards in new build housing which come into force in February this year and the prohibition from 2024 of the use of direct emissions heating systems for hot water heating and cooling.

The new minimum environmental design standards will create a new Scottish version of the current Passivhaus standards. Passivhaus standard is generally accepted to be an energy efficient design standard which captures heat from the sun and activities of the occupants to maintain almost constant temperature inside the dwelling, with little need for additional heating or cooling.

A Passivhaus differs from carbon neutral buildings which use a combination of energy efficiency and clean energy generation to effect energy use. Using the Passivhaus standard, dwellings use less energy in the first place by in effect being sealed from the elements. Construction methods may vary, but dwellings are likely to have triple glazing, greater insulation, around twenty times more air tightness levels than in the standard new builds and mechanical ventilation with heat recovery systems attached. A Passivhaus runs in a way to reduce the need for heat, but there is another heating mechanism attached to the property which would kick in if the temperature drops below zero, which may be fairly often in Scotland at the moment! There still needs to be a mechanism to heat water such as solar or air source heat pump which have no emissions at the point of use.

During consultation on Mr Rowley's proposed Bill, concerns were raised about the cost of implementing a Passivhaus standard and the lack of experienced human resource available to effectively implement Passivhaus in the construction sector which may lead to delays in delivery. Many, including Homes for Scotland, felt that the current direction of travel in building standards improvements is already sufficient to ensure improved energy in new build housing.

The Scottish Government will carry out its own consultation on the proposed legislation which will provide the housebuilding industry with further opportunities to help shape Scotland's "Passive Hoose" standard.