the year of change


Key Part L considerations • Increased air permeability and pressure testing


• Submission of TER and DER information


• New limiting U-Values


• Demonstration of energy efficiency building shells and core units


Part F – Balancing


airtightness with ventilation Revisions to Part F have been developed to correspond with the changes to Part L and ensure minimum energy efficiency levels are in place for all ventilation systems. One of the most significant changes is the use of trickle ventilation, which looks to become more challenging under the new regulations. Additional guidance published for dwellings with air permeability tighter than 5.0m3/(h.m2), states that approximately 50 per cent more background ventilation will be required for dwellings with intermittent or passive stack ventilations systems. Passive stack ventilation systems will also require internal pipes to be sized at 125mm serving all spaces, an increase on Part F 2006.


This change in air permeability


requirements may result in more designers and builders opting for continuous ventilation systems, which are better performing in SAP 2009, simpler to standardise and do not require trickle vents. As such, under the new Part F, for dwellings with continuous ventilation systems, there will be no need for background ventilation where air permeability rates are above 5.0m3/(h.m2). A further benefit is that designers may be more likely to adopt whole house mechanical extract ventilation systems, potentially including heat recovery.


Under the new Part F, fixed mechanical ventilation systems will, where possible, also require testing and commissioning, and both intermittent and continuous mechanical ventilations installations


will need to have air flow measured. This includes installations such as cooker hoods and bathroom extractor fans. Within five days of completion, data must be sent to the building control body, adding another procedure to follow at the completion stage. A further requirement will be to ensure sufficient information is handed over to the building owner if systems have been installed in a new dwelling.


Key Part F considerations • Testing fixed mechanical ventilation systems


• Providing sufficient information on ventilation systems and installation to home owners


• Changes to size of internal passive stack ventilation pipes


Part J – Making homes safer The most significant change to Part J is the requirement for carbon monoxide alarms to be installed in all dwellings with solid or biofuel combustion appliances The new regulations state that the alarm should have a long term power supply, be sited between one and three metres of the combustion appliance and must be able to detect the release of carbon monoxide and sound an alarm. There is also new guidance for dwellings to provide additional containment protection for oil tanks of up to 3,500 litres. This means that if a dwelling is located within Zone 1 of the Environmental Agency Groundwater Source Protection Zone map, then secondary containment is required. Flues have also been the focus of several changes to Part J, with detailed guidance being published for the provision of access to concealed flues and chimney systems. In basic terms this means that a 300mm x 300mm access should be provided at strategic locations to check that the flue is continuous and adequately supported throughout its length, that joints are correctly assembled and sealed, and that any required gradient to drain points for


condensate are provided. It is also important that flues are designed not to pass through other dwellings and access should not compromise fire safety, thermal or acoustic provisions.


In addition, to correspond with changes to Part L, dwellings with air permeability of less than 5.0m3/(h.m2) will be subject to additional ventilation requirements for open flued appliances. For example, an appliance with a rated output up to 50kW should have 850mm2/kW of permanent ventilation for this level of air permeability as opposed to 550mm2/kW for leakier dwellings.


It is important that home builders understand how to meet the new requirements and help make homes more airtight and, therefore, more energy efficient.


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Key Part J considerations • Requirement for carbon monoxide alarms to be fitted in dwellings with solid or biofuel combusPart L – Making homes more energy efficient


British Builder & Developer 15


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