Building tight – ventilating right? How are new air tightness standards affecting indoor air quality in dwellings?

Abstract

Abstract:Building more air-tight dwellings is having a deleterious impact on indoor air quality. In a range of recently completed dwellings CO2 concentrations were measured in occupied bedrooms at unacceptable concentrations (occupied mean peak of 2317ppm and a time weighted average of 1834ppm range 480 -4800ppm). Such high levels confirm that air tight dwellings with only trickle ventilators as the 'planned' ventilation strategy do not meet the standards demanded by the Building Regulations. Reducing ventilation rates to improve energy efficiency and lower carbon emissions, without providing a planned and effective ventilation strategy is likely to result in a more toxic and hazardous indoor environment, with concurrent and significant negative long term and insidious impacts on public health. Furthermore, the methodology underpinning the current regulations cannot be considered as creditable. Any researchers operating in this field require to recognise that dwellings have internal doors. (6) and Crump et al (7) , who called for further investigations to ascertain 'healthy' ventilation rates. This was partially addressed in a recent study (8) commissioned by the Scottish Government, "The effect that increasing air-tightness may have on air quality within dwellings". In this study air tightness and air change rates were measured in a mid-terrace dwelling (Garston, Watford) under a variety of conditions and the published report concluded that dwellings built to 5m 3 /m 2/ /hr@50Pa provide air change rates roughly in line with the CIBSE (9) recommendation of 8l/s per person. BRE test results 2.1In a mid-terrace dwelling, with an air tightness reduced to 6m 3/ /m 2 /hr@50Pa with standard trickle vents fitted on all windows, ventilation rates were measured at 0.7 to 1.3ach -1 on the upper floor (equating to 37-69 l/s), and 0.4 to 0.6 ach -1 on the ground floor (equating to 21-32 l/s). Measurements of CO 2 concentrations (released from a mechanical source) did not provide any cause for concern and settled at circa 1000ppm in the living room and 600ppm in bedrooms. 2.2 3.2The living room and double bedroom were repeatedly pressure tested with the MHVR system outlets/inlets sealed and the system disconnected from the power supply. By progressively increasing the opening area of an additional vent in the tarpaulin, the target air leakage/infiltration rate of 5m 3 /m 2 /hr@50 Pa was achieved. The rooms were then re-occupied Four data sets were collected over two 24hours occupied periods. The initial set measured CO 2 , temperature and humidity -with the MHRV system disabled -between 1800-2200hrs in the living room and 2300-0700hrs in the master bedroom The second two data sets measured the same parameters with the MHRV system re-activated. ResultsGraph 1:Living room MHRV disabled Graph 2: Bedroom MHRV disabled 4. Discussion 4.1 When the living room door is closed and the room occupied by 2 adults and 3 children, CO 2 levels climbed at a rate of 514ppm/hour, peaking at just over 2600ppm. At this time the children star...

Meta-analysis of indoor temperatures in new-build housing

“…However, while previous work has evidenced problems with ventilation and indoor air quality in modern homes (Crump et al, 2009;Howieson et al, 2013;Sullivan et al, 2013), overheating is often a component of this. In some instances, heat reduction through ventilation is a low-cost activity (for example, summer ventilation of solar gain, or night-time ventilation under 'free-running' mode (Ucci et al, 2011), however during the heating season, venting of incidental gains from energy sources (space and water heating, electrical items) will likely incur an energy penalty.…”

An Investigation of Indoor Air Quality in UK Passivhaus Dwellings

“…Initial findings indicate IAQ concerns in bedrooms of contemporary dwellings [15], with particular issues in relation to the provision of adequate ventilation [16]. Similarly, apprehensions have been expressed regarding overheating in Passivhaus dwellings and significant discrepancies have been observed between measured and predicted indoor temperatures using Passive House Planning Package software [17].…”

Indoor air quality and occupant comfort in homes with deep versus conventional energy efficiency renovations

“…Although on average parameters met M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 13 generally accepted standards for indoor air quality, we did observe a few measurements of elevated tVOCs and reduced temperatures. Some individual measurements of tVOCs were substantially higher than the median value; this frequently correlated with a staff observation of some activity (such as use of air fresheners immediately prior to the study visit) that could result in the introduction of VOCs into the home.…”

“…However, there is limited data on whether this is achieved in practice, and even less for extremely efficient homes, such as deep energy retrofit or net zero energy homes [3,[13][14][15][16].…”