Passive house: an alternative method of meeting Part L?

The equivalent of England’s Approved Document L1A, Ireland’s Technical Guidance Document L for dwellings demands 60% energy and carbon reductions compared to 2005 levels, and requires renewable energy generation – 10kWh/m2/yr of thermal energy or 4kWh/m2/yr of electrical. These changes were heavily influenced by the campaigning work of this magazine’s predecessor, Construct Ireland.

But as with the UK regulations, the detail on compliance is contained within guidance documents, rather than in the regulation of Part L itself. As legal expert Philip Lee writes in the Irish edition of Passive House Plus issue 9, guidance documents don’t have the force of law, meaning alternative methods of compliance – such as passive house – could conceivably be used.

Curiously, buildings that go beyond Ireland’s 60% energy reductions can struggle to meet Ireland’s renewable energy targets, as they may not have sufficiently high energy demand to easily meet the 10kWh/m2/yr renewables target. Irish passive house advocates have long argued that dwellings meeting the standard should not be required to generate such quantities of renewable energy.

According to Lee: “It could be argued that the proportion of renewable energy to fossil fuels inherent in the technical guidance document could also be applied to a passive house. Therefore, if a passive house consumes 50% less primary energy, then the “proportion” of renewables set out in the technical guidance document, namely 10 kWh/m2 (heating) and 4 kWh/m2 (electrical energy), should be reduced by 50% to 5 kWh/m2 and 2 kWh/m2 respectively.”

“An alternative approach to the same interpretation of “reasonable” would be to look at the net balance of brown energy that is produced in a standard house and compare that to the net brown energy produced in a passive house. Provided that the net amount of fossil fuel being consumed in the passive house is less than that being consumed in a standard house then it could be argued that any actual energy coming from renewable sources would meet the ‘reasonable test’.”

Lee also points out that under the RES Directive, EU members states must “require the use of minimum levels of energy from renewable resources” both in new buildings and existing buildings that are subject to major renovation, from 31 December 2014. This means, he says, that Ireland’s Part L will be in breach of the directive if it is not quickly updated, as it specifies a “proportion” of renewable energy rather than a minimum amount. He warns that targets set in a guidance document don’t suffice, given their non-mandatory status. The four regions of the UK are also set to be in breach, based on current policy.

Lee points out that the directive encourages member states to take into account “national measures relating to substantial increases in energy efficiency” and to “passive, low or zero energy buildings” when updating their building regulations to increase the share of renewable energy.