SPONSORED FEATURE | How will the energy performance directive impact building design in 2019? The next update to Part L, due to be released for consultation this spring, looks set to move the goalposts for building compliance and create a shift of focus from carbon emissions to primary energy in line with the Energy Performance of Buildings Directive. Matthew Maskell, applications design engineer at Glen Dimplex Heating & Ventilation (GDHV), considers how primary energys introduction must be targeted correctly to continue our path towards a sustainable future 2 019 is going to be a big year for building designers as they work to understand the implications of the planned overhaul to Building Regulations. Energy use under Part L (alongside its devolved-power equivalents) currently drives HVAC strategy in new buildings, focusing building designers on reducing carbon emissions. While reducing carbon emissions remains an important part of building design, government policy and the achievement of the fourth and fifth carbon budgets set in the Climate Change Act, it is no longer the only measure with which building designers are going to have to contend. From 31 December 2020, all new buildings will have to demonstrate that they are nearly zero energy buildings (NZEB) in order for the UK to comply with Article 9 of the Energy Performance of Buildings Directive, and this must be measured in primary energy. This move will see a new target put into place for all new developments. These targets define the maximum kWh/m2 allowed in buildings for all energy use, combining appliances, heating, cooling and hot water. The UK has yet to state what this target may be and whether build types that use less energy, such as apartments, will have a lower target than more energy intensive dwellings such as houses. Other European countries, such as France and Poland, have implemented a maximum permissible value of between 50 and 65 kWh/m 2, depending on build type. When set, this new primary energy target will add an interesting dimension to building design as it seeks to address the wider issue of reducing energy consumption in our buildings rather than simply enforcing the lowest carbon technology. What is primary energy and what impact will it have on HVAC specification? Primary energy is a reflection of how much raw fuel, also known as primary energy, is used to generate a unit of final energy. This includes the energy used to create, transform and transport the fuel from its raw form to where it is used. The proposed UK factors for gas and electricity were included in the recently revised SAP10 methodology, but they have not received as much attention as the more radical changes in the carbon emission factor for electricity. This is because, with this change, a gas boiler at 90% efficiency will consume 1.1 kWh per 1kWh of heat delivered, equivalent to 0.231kg of carbon under the new proposed values. As electric heating is 100% efficient at the point of use, 1kWh of electricity will be consumed when producing 1kWh of heat, equivalent to 0.233kg of carbon under the new proposed values. As a result, if you consider carbon in isolation, a 90% efficient gas boiler is now equivalent to an electric heating system, which in a carbon-focused method of compliance could create a 0.210 kgco2 per kWh 0.233 kgco2 per kWh 30 March 2019 www.cibsejournal.com GDC DPS Adv.indd 30 21/02/2019 14:19