Air Quality Feature
Air exchange targets
Richard Poole from Siegenia addresses how and why housing managers should meet the new air exchange targets
dwelling or all other buildings in England. It therefore sets the standards for the ventilation of both new and existing buildings and needs to be considered by any housing management companies considering undertaking upgrades to their stock.
T
WHY IS PART F CHANGING? Te outgoing Part F has been in place since 2010, but over the years key issues have been identified and concerns have been voiced over the failure of homes complying. In 2020, guidance from Public Health England on selected volatile organic compounds (VOCs) indoors and World Health Organisation (WHO) recommendations for indoor pollutant levels meant Part F, as it stood, was out of date. Part F is also very closely linked with Part L (conservation of fuel and power),
as both are being improved to meet the Government’s Future Homes Standard. One way of improving energy efficiency is to reduce the heat loss through air permeability, thus building more airtight homes. However, an increased air tightness leads to reduced ventilation and, therefore, Part F requires updating to ensure that sufficient levels of ventilation are still provided.
CHANGES TO APPROVED DOCUMENT PART F
• Simplifying the approach for determining the ventilation rate and system design requirements for a dwelling
• Changing the way that ventilation systems are presented in the Approved Document to reflect common design practices and latest evidence relating to air quality in homes
• Introducing guidance to reduce the ingress of external air pollutants into the main body of the Approved Document
• Simplifying the structure and content of the guidance
WHY THE CHANGE NOW? Ventilation remains an ongoing challenge not just for private developers and self-builders, but also for those of us undertaking any refurbishment works on properties. With increasing air tightness standards in the UK for new build homes and the focus on procuring the most energy efficient products, we end up creating nothing more than highly efficient sealed boxes. Tis may sound ideal (and from an energy conservation point of view it is) but without a properly considered holistic ventilation strategy, poor indoor air quality and issues of condensation and mould will ensue and become a recurrent problem for housing managers and landlords.
WHY DO HOMES REQUIRE VENTILATION? Ventilation specialists will generally quote a ‘maximum’ air tightness of 4-5m3/hm2 as a healthy rate for a naturally ventilated house. Tat is, ventilated only with extract fans, trickle vents and windows. Anything tighter and some form of forced ventilation will be required.
he updated new building regulation Approved Document F covering ventilation came into force on 15th June 2022. Part F concerns construction projects that are new or result in the change of use of a
Heating, Ventilation & Services
Decentralised whole-house heat recovery ventilation is less understood but offers some significant benefits over its centralised cousin
According to the Environmental Protection Agency, the levels of indoor air
pollutants can be two to five times higher than outdoors. Te primary function of a ventilation system is to reduce the moisture in the air. Te average family of four produces about 15 litres of moisture each day from activities such as bathing, cooking, washing and breathing. Ventilation also helps dilute the effects of carbon dioxide (CO2) released
through breathing, smoking, cooking and burning fossil fuels. CO2 levels are measured in parts per million (ppm). Normal outdoor ambient air is regarded as 250-400ppm and safe levels between 400-1000ppm is typical of indoor spaces with good air exchange.
THE TRADITIONAL TRICKLE VENT SOLUTION Trickle vents are considered under the topic of ‘background ventilation’ in the new approved document F, stating that these will be a legal requirement for the majority of window installations in England. Te new legislation also clearly sets out the ventilation requirement of any habitable room and defines this by “equivalent area” (EA) measured in millimetres squared. For example, a host room that will have no openable windows once an extension or conservatory has been added will need 10,000 mm² EA for ventilation, while an existing bathroom will require trickle vents of 4,000 mm² EA. Trickle vents are very effective at allowing the exchange of outdoor air with
indoor air in the same way that an open window does but in a much more controlled way. Unfortunately, however, in the bid to seal up our homes to prevent heat loss they have oſten been omitted by the developer or later blocked up by the homeowner.
ALTERNATIVE VENTILATION METHODS TO CONSIDER Te new legislation allows several options (or work arounds) to further improve ventilation performance and/or energy conservation. Centralised whole-house heat recovery systems have been around for some time and have oſten been
www.housingmmonline.co.uk | HMMAugust/September 2022 | 45
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
