What is Part L?

If you built your house recently, you will be familiar with the `Part L’ regulations which is a Technical Guidance Document of the Irish Building Regulations. It focuses primarily on the ‘conservation of fuel and power’ and places emphasis on heat loss through walls, lintels, floors and roofs. The Standard Assessment Procedure (SAP) used to measure compliance with these regulations calculates the dwellings’ overall efficiency taking many varying factors into account.


Part L updated in April 2014 has introduced a new set of targets called the ‘Target Fabric Energy Efficiency’(TFEE) rate, focusing on the external envelope of a building’s design.

This document has been published by the Minister for the Environment, Community and Local Government. The guidance in this document applies to dwellings, both new and existing.




In general, the regulation stipulates that a building shall be designed and constructed so as to ensure that its energy performance is such as to limit the amount of energy required for the operation of the building and the amount of carbon dioxide (CO2) emissions associated with this energy use insofar as is reasonably practicable.


Building Energy Rating (BER):


The BER is an indication of the energy performance of the dwelling. It covers energy use for space heating, water heating, ventilation and lighting, calculated on the basis of standard occupancy. It is expressed as primary energy use per unit floor area per year. (kWh/m2/yr).

‘A’ rated properties are the most energy efficient and will tend to have the lowest energy bills.

It should also be noted that a key pillar of Part L of the Regulations is that each new dwelling should have a specified minimum level of energy provision from renewable technologies. To meet these requirements, people are increasingly considering the use of such technologies as Air to Water or Geothermal Heating Systems, Solar Panels and Biomass Boilers.

Solar thermal and Solar PV can both be used to achieve or help achieve compliance with the requirement. However, due to the ease of installation and more diversified use of the energy it produces, Solar PV is fast becoming the favoured method of the two types of technology.

The BER assessment procedure (DEAP – Dwelling Energy Assessment Procedure) is the only method which can verify whether or not a Solar installation meets the renewable requirements.

The DEAP manual describes the Dwelling Energy Assessment Procedure (DEAP), which is the Irish official procedure for calculating and assessing the energy performance of dwellings. DEAP calculates the energy performance of new and existing dwellings. The procedure takes account of the energy required for space heating, ventilation, water heating and lighting, less savings from energy generation technologies. For standardised occupancy, it calculates annual values of delivered energy consumption, primary energy consumption, carbon dioxide emissions and costs, both totals and per square metre of total floor area of the dwelling.


How does the new regulations affect the design process?

All new dwellings must have an Energy Assessment completed to show compliance with the new Regulations.

The Standard Assessment Procedure (SAP) is the methodology used by the Government to assess and compare the energy and environmental performance of dwellings. Its purpose is to provide accurate and reliable assessments of dwelling energy performances that are needed to underpin energy and environmental policy initiatives. 

At Power Capital, we design and install Solar PV systems for clients across the whole construction sector, including residential developments, commercial, retail, education, agriculture and public sector. Our bespoke solutions are ideal for organisations and companies looking to reduce their carbon footprint or benefit from the reduction in energy costs a PV system can offer.

Power Capital makes Solar easy for you. 

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"SEAI - Solar Building Regulations". Seai.ie. N.p., 2016. Web. 26 July 2016.

Conservation Of Fuel And Energy - Dwellings. 1st ed. Dublin: Published by the Stationery Office, 2016. Web. 26 July 2016.

Building Regulations and The Future Of Energy Efficient Buildings. 1st ed. Environment, Heritage and Local Government, 2016. Web. 26 July 2016.

"Ber Rating Explained - BER Ratings Ireland". BER Ratings S Ireland. N.p., 2013. Web. 22 July 2016.

"Brief Guide To Part L Building Regulations For Dwellings". Fallon Consulting Engineer. N.p., 2015. Web. 26 July 2016.

"Standard Assessment Procedure - Detailed Guidance - GOV.UK". Gov.uk. N.p., 2013. Web. 26 July 2016.