Ventilation: Approved Document F, Volume 1 — Dwellings

B O N L I N E V E R S I O N Table B1 Indoor air pollutants guidance values(1)(2) Pollutant Exposure limit Exposure time Carbon monoxide (CO) 100mg/m3 15-minute average 30mg/m3 1-hour average 10mg/m3 8-hour average Nitrogen dioxide (NO ) 200μg/m3 1-hour average 2 40μg/m3 1-year average Formaldehyde (CH O) 100μg/m3 30-minute average 2 10μg/m3 1-year average TVOC(3) 300μg/m3 8-hour average NOTES: 1. No safe levels can be recommended for benzene or trichloroethylene so they have not been considered in the definition of ventilation rates in dwellings. The best strategy for reducing their concentration indoors may be to control them at source. 2. Even if the designer and builder choose to reduce volatile organic compound (VOC) levels in dwellings by controlling them at source, the ventilation requirements must still be met. 3. The total volatile organic compound (TVOC) metric is representative of all airborne indoor air VOC concentrations and should not be used as a direct indicator of health. The simplified metric is used as an indicator for the purpose of ventilation control strategies. As an alternative to the TVOC limit, individual VOC limits may be used where justified in accordance with the guidance in paragraph B5. B5 As an alternative to using TVOC, the individual VOCs may be applied where their use is supported by robust independent evidence. Public Health England’s Indoor Air Quality Guidelines for Selected Volatile Organic Compounds (VOCs) in the UK should be used. Testing against these metrics is likely to be more complex than testing against TVOC. B6 Control of bio-effluents (body odours) for people who have been exposed to the environment for a period of time will be achieved by an air supply rate of 4 litres per second per person (BS EN 16798-1). Assumptions used in applying performance criteria for dwellings in Section 1 General B7 Where the guidance for less airtight dwellings is followed, dwellings are assumed to have an infiltration rate of 0.15 air changes per hour. B8 Where the guidance for highly airtight dwellings is followed, dwellings are assumed to have an infiltration rate of 0 air changes per hour. B9 Ventilation effectiveness is assumed to be 1.0 – that is, it is assumed that supply air is fully mixed with room air. CIBSE’s Guide A Environmental Design provides further information on ventilation effectiveness. 40 Approved Document F Volume 1, 2021 edition Building Regulations 2010 O N L I N E V E R S I O N