Modern Building Services

MODERN BUILDING SERVICES APRIL 2023 29 FEATURE INDOOR AIR QUALITY W e don’t seem to be able to talk about any challenges these days without adding the word crisis afterwards. Climate change crisis, cost of living crisis, energy crisis and air quality crisis. The latter two are intrinsically linked, and in many cases have opposing priorities. The latest version of Approved Document L of the building regulation, conservation of fuel and power came out in 2014, but has been updated as of 3rd February 2023. The latest version of Approved Document F (ADF) was updated in 2022. Both approved documents took effect on 15 June 2022 for use in England. They do not apply to work subject to a building notice, full plans application or initial notice submitted before that date, provided the work for each building is started before 15 June 2023. Despite being launched after the updatedWorld Health Organisation (WHO) pollution limits were released, the update of part F does not include particularly stringent levels for outdoor pollution drawn into buildings. This is amissed opportunity to improve people’s health and comes as a surprise given increased awareness about the health impacts caused by air pollution and, considering the long periods of time that these documents remain in force. The latest in a long line of air quality linked scientific reports indicates that air pollution is linked toworsening symptoms of osteoporosis. Approved Document F: Section 2: Minimising the ingress of external pollutants. This section states that “ventilation systems should be designed to minimise the intake of external air pollutants” if “the pollutant values in the location of the building exceed any of the limits in Table 2.1” or if the building is located near to any sources of significant local pollution. Section 2.6 of ADF states that where sources of pollution vary with the time of day, such as urban road traffic, it may be acceptable, for time-limited periods, to take one of the following actions. a. Reduce the flow of external air into ventilation intakes b. Close ventilation intakes when the concentrations of external pollutants are highest This allowance is a great opportunity for reducing energy, reducing filter change intervals AND improving indoor air quality. It is an acknowledgement that sometimes outdoor air is not always “fresh air”, and that the decision whether to be ventilate should be based on data rather than assumptions. There are two data source options for controlling ventilation rates according to outdoor pollution levels. The first is to mount an outdoor air quality sensor near the AHU intakes. The second is to connect the BMS to an outdoor air quality API with live modelled data. If outdoor pollution levels are consistently higher than those included in ADF Table 2.1, or if the building being constructed is targeting healthy building standards like WELL or AirRated, appropriate air cleaning solutions will need to be applied to the AHUs bringing air in from outdoors. Where any of the following components are included within HVAC installations, the maximum specific fan power (SFP) for an air distribution may be increased. a. High-efficiency particulate air (HEPA) filter: add 1.0W/(l·s) b. Humidifier/dehumidifier: add 0.1W/(l·s) c. Active chilled beams: add 0.3W/(l·s) d. Transpired solar collector: add 0.3W/(l·s) For the majority of buildings these are all fairly niche pieces of equipment, which means their extra energy consumption allowance, on the whole, is not having a big impact on the built environment. No allowance is given in Part L for the particulate or molecular filtration required to satisfy ADF section. Headaches when complying This is going to give building designers a real headache when trying to comply with both pieces of legislation. It does not seem that the government is going to take significant action to address air pollution in the short term. ➜ By James Price , Head of Specification, Spire Building Services Ltd Part L vs Part F - Battle of the regulations Pollutant Exposure limits from Part F Exposure time WHO guidance 2021 Carbon Monoxide 10mg/m3 8-hour average N/A Carbon Monoxide N/A 1-day average 4mg/m3 Sulphur Dioxide 350µg/m3 1-hour average N/A Sulphur Dioxide 125µg/m3 1-day average 40µg/m3 Nitrogen Dioxide 200µg/m3 1-hour average N/A Nitrogen Dioxide 40µg/m3 1-year average 10µg/m3 Nitrogen Dioxide N/A 1-day average 25µg/m3 Benzene 5µg/m3 1-year average N/A Lead 5mg/m3 1-year average N/A PM2.5 25µg/m3 1-year average 5µg/m3 PM2.5 N/A 1-day average 15µg/m3 PM10 50µg/m3 1-day average 15µg/m3 PM10 40µg/m3 1-year average 45µg/m3 Ozone N/A 8-hour average 100µg/m3 Table 2.1 From ADF with the addition of WHO 2021 limits Outdoor air quality sensor”