The new rules for ventilation
Lee Nurse reviews the impact on energy consumption and carbon emissions of the Building Regulations for ventilation in new housing.
The new Approved Documents Part F (‘Means of ventilation’) and Part L (‘Conservation of fuel and power’) of the Building Regulations have changed the outlook on the choice of ventilation solution for specifiers in the new-build sector. They feature a number of major revisions that include minimum levels of energy efficiency for all ventilation systems.
The launch of Part L’s new ‘Domestic building services compliance guide’ highlights ventilation performance levels, and a specific fan power requirement of less than 0.5 W/l/s is now included to cover intermittent fans for new-build developments.
The regulations also require that homes are increasingly airtight to further reduce carbon emissions — but not at the expense of good air quality. So, Part F offers guidelines for airtight properties with infiltration rates tighter than 5 m3/h/m2 at 50 Pa. For Intermittent System 1 and Passive Stack System 2 approaches, in airtight dwellings the guidance increases background ventilation rates by up to 50%. Since this level is difficult to achieve with trickle ventilators in windows, this new demand will increase the uptake of continuous ventilation solutions at the expense of intermittent fans. Continuous ventilation performs better in SAP, is easier to specify and easier to standardise.
The result will be a growth in the specification of whole-house and decentralised mechanical extract ventilation systems (MEV and dMEV) and mechanical extract ventilation systems with heat recovery (MVHR).
Meanwhile, for the first time Part F requires post-completion testing of ventilation equipment. Part F’s new ‘Domestic ventilation installation and commissioning compliance guide’ has been introduced to ensure ventilation not only delivers the required airflow but also does it efficiently and quietly. The guide includes sign-off procedures and paperwork completion to ensure performance and efficiency are met. Post-installation performance policing is critical to ensure air quality in increasingly airtight homes. This is especially important with the increased adoption of highly efficient ventilation systems, like MVHR, which require trained competent installers.
It is at this point that leading players, like Vent-Axia, have an important role to play. That’s why we have introduced a dedicated and comprehensive Vent-Axia Lo-Carbon ventilation range which meets the approved document’s specific fan power requirements of less than 0.5 W/l/s for all applications. Our ventilation is also supported by access to extensive technical advice, expertise in design and ventilation applications to help understand low-carbon ventilation issues, advising on how best to reduce energy consumption and cut emissions on a diverse range of projects. We are constantly pushing the boundaries to create innovative solutions to meet the changing requirements of the industry and to comply and stay ahead of current legislation.
For example, solutions such as our Lo-Carbon Centra dMEV comply with Part F for continuous mechanical extract ventilation (System 3) and are capable of achieving ventilation using only 1.4 W. Thus they meet the requirements of the regulations as far as specifiers are concerned but also ensure that electricity bills for homeowners won’t hit the roof. Offering virtually silent operation, a fresh design and a reduction in the requirement for trickle ventilators potentially to zero, these energy-efficient systems fit discreetly in modern homes and are simple to install.
Residential mechanical ventilation with heat recovery (MVHR) systems, such as the Sentinel Kinetic, offers a SAP Appendix Q eligible ventilation solution capable of up to 92% heat recovery. This will help reduce the DER (dwelling emission rate) of new-build properties and deliver points to meet Level 3 and Level 4 of the Code for Sustainable Homes.
Indeed, together, the Code for Sustainable Homes and the Building Regulations map out the journey towards the zero-carbon homes target in 2016. As homes become inevitably more airtight to meet the demands of the new Building Regulations, so it will become key to specify more energy-efficient ventilation solutions, such as MVHR. But meeting the challenge of zero-carbon homes is about more than just making a product selection; we need to work together to consider correct specification, installed performance of products and ongoing maintenance and system design — which are all necessary to meet our shared goal of achieving good, low-carbon ventilation.
Lee Nurse is marketing director with Vent-Axia
