Literature review: Domestic Ventilation Practices Lisa Gobio-Lamin, PhD Candidate 10 th May 2012.

Literature review: Domestic Ventilation PracticesLisa Gobio-Lamin, PhD Candidate

10th May 2012

IntroductionIntroduction

• More energy is used in housing than in any other

sector in the UK.

• Space heating is responsible for around 65% of the

UK’s total household energy use.

• Domestic energy consumption rose by 31% from

1970 to 2009 with the largest increase occurring in

heating energy use (DECC, 2011).

• Increase in energy for space heating can be attributed to the size of dwellings and rooms being heated, occupants’ comfort preferences, window-opening behaviour and the external temperature.

• Householders’ increased standards of comfort have been blamed for home energy use not declining despite improved dwelling energy efficiency.

• Study found no statistical evidence for any change in reported thermostat setting between 1984 and 2007 (Shipworth, 2011).

• If householders are not demanding higher indoor temperatures now than they did twenty years ago, then what other factors could be influencing domestic heating energy use?

• A building’s heating energy use is significantly influenced by occupant’s behaviour such as the opening of windows & doors when the heating is on (Garland, et al. 1993; Anderson, 2009).

• Window opening behaviour was found to have the largest effect on air change rates which can significantly influence a building’s energy consumption (Wallace, et al., 2002).

• This highlights the importance of investigating occupants’ window opening behaviour in winter.

Domestic Ventilation PracticesDomestic Ventilation Practices

Direct observation of window opening behaviour was conducted for 120 dwellings in Cambridgeshire in winter of 2006-07 by Fox, 2008.

Dwellings consisted of detached, semi-detached, terraced houses and flats.

The highest percentage of open windows were in the morning during the breakfast period than at other times of the day. Result is consistent with the IEA Annex VIII study conducted in the Netherlands (Dubrul, 1988).

A higher proportion of open windows at the weekend than during the week by Fox, 2008 and also in a study in Netherlands by Jacobs et al., 2010.

In flats and houses, a higher percentage of windows were open during the breakfast period than at other times (Fox, 2008).

However in flats, bathroom windows were opened most frequently than any other windows during the breakfast period.

In houses, bedroom and bathroom windows were opened the most during breakfast time. This is consistent with a study by Brundrett, 1977.

Number of open windows decreased during the rest of the day in houses, with a slight increase occurring after late afternoon into the evening which decreased overnight (Fox, 2008).

A higher proportion of occupants reported opening their windows in the morning and at night than any other period of the day (Wouters & De Baets, 1986).

Factors that influence domestic ventilation practicesFactors that influence domestic ventilation practices

There are a number of factors that affect ventilation behaviour in dwellings. They include:

Outdoor Climate

Indoor climate preference

Dwelling Type

Window Design

Perceived indoor air quality

Household composition

Occupancy & Time of Day

Household Activities

Outdoor climateOutdoor climate

Direct linear correlation between window use and external temperature when the outdoor temperature range was between -10C to +25C was found (Dubrul, 1988).

Direct correlation with the number of opened windows and external air temperature (Fox, 2008 & Jacobs et al., 2010).

A negative linear correlation between wind velocity and window opening was observed in the German study, Annex VIII project (Dubrul, 1988).

A slight correlation between wind speed and number of open windows was found by Fox, 2008.

Indoor climate preferenceIndoor climate preference

• Indoor climate preferences had a strong correlation with the way windows were used.

• The studies from the IEA Annex VIII project showed that the higher the occupants’ preferred thermostat setting, the less windows were opened (Dubrul, 1988).

• The preferred temperature in the bedrooms was lower than in the living rooms. Bedroom windows were opened for much longer periods than the windows of other rooms.

• Some of the windows in the main bedroom were kept open during the night even in cold winter conditions (Dubrul, 1988).

Dwelling TypeDwelling Type

• Dwelling type influenced the length of time windows were open as well as the width/size of the opened windows (Wouters & De Baets, 1986).

• In houses, bedroom windows were open for longer than in flats. Living room and kitchen windows were found to be open for shorter periods in houses than in flats (Wouters & De Baets, 1986; Van Dongen, 1986).

• In flats, the bathroom had the highest proportion of open windows whilst the kitchen had the lowest number of open windows. The lowest proportion of open windows in houses and flats were in the kitchen (Fox, 2008).

• In flats, a higher proportion of windows were reported to be slightly open than wide open, which was the opposite in houses (Wouters & De Baets, 1986).

Window DesignWindow Design

• The design of a window, with regard to how it is hung in its frame and the direction of travel of the opening part, influenced window opening (Dubrul, 1988).

• Belgian research showed that bottom hung windows which open inwards were opened more frequently than other types.

• The German team found that during the winter months there was very little difference in the duration of opened sash windows in the side-hung or bottom-hung position.

• During the rest of the year, sash windows were opened in the side-hung position for a longer period than in the bottom-hung position (Erhorn, 1986).

• Bedroom windows were opened in the side-hung position for a longer duration of time than in the bottom-hung position (Dubrul, 1988).

• Living room windows were opened in the bottom-hung position for a longer duration of time. This supports the findings that bedrooms are ventilated more than living rooms in winter.

• Ventilation grilles were opened three times longer than casement/pivot windows in Dutch dwellings. The duration of open fanlight windows were also twice that of casement/pivot windows in the whole dwelling (Van Dongen & Phaff, 1989).

• Reasons for these differences in use could be that different designs offer different areas of opening and that some window designs are easier to open.

Perceived indoor air quality Perceived indoor air quality

• A high proportion (63%) of occupants reported ‘dry indoor air’ and ‘the air smelling bad’ as the reasons for opening their windows in winter (Andersen, 2009).

• Some of the most frequent responses provided by occupants for opening their windows in winter were to freshen up their dwelling, remove bad smells, avoid stuffiness and to get rid of smoke (Brundrett, 1977; Wouters & De Baets, 1986).

• The living room was ventilated for twice as long in dwellings where occupants smoked than in non-smoking households (Van Dongen, 1986).

• The need for fresh air in winter, especially in bedrooms was connected with health related beliefs.

Occupancy & Time of DayOccupancy & Time of Day

• Highest proportion of open windows were in the morning during the breakfast period, followed by a large decrease during the rest of the day in both flats and houses (Fox, 2008).

• Higher proportion of occupants reported opening their windows in the morning and at night than any other period of the day (Wouters & De Baets, 1986).

• Houses where the housewife did not work but stayed home had twice as much windows open than houses where the housewife was in full-time employment (Brundrett, 1977).

Household compositionHousehold composition

• The Belgian team discovered that households with occupants aged 18-44 years opened their windows more frequently and for longer than those with occupants aged over 45 years old (Dubrul, 1987).

• A possible reason could be that older occupants are more sensitive to cold air.

• There was no clear trend found in the relationship between household size and window opening behaviour in the IEA Annex VIII studies.

• A positive correlation between the number of open windows in dwellings and the household size was found by Brundrett, 1977.

Household ActivitiesHousehold Activities

• Occupants’ reported opening their windows when did household activities such as vacuum cleaning and airing bedclothes (Van Dongen, 1986).

• In kitchens, window opening was related to cooking activities, cooking smells and vapour problems.

• In the Belgian and Dutch studies a positive correlation was found between the use of showers and the use of the bathroom windows (Dubrul, 1988).

• Amongst occupants’ most popular reasons for opening their windows was to remove condensation (Andersen, 2009 & Wouters & De Baets, 1986).

References

Andersen, R.V., 2009. Occupant behaviour with regard to the control of indoor environment. PhD. Technical University of Denmark.

Brundrett, G., 1977. Ventilation: A Behavioural Approach, Energy Research, pg 289-298.

DECC, 2011. Domestic energy consumption in the UK since 1970 [pdf], Available at:<http://www.decc.gov.uk/assets/decc/11/stats/publications/energy-consumption/2323-domestic-energy-consumption factsheet.pdf> [Accessed 18th February 2012].

Dubrul,C., 1988. Inhabitant Behaviour with Regard to Ventilation, IEA Annex VIII Report.

Erhorn, 1986. Influence of the meteorological conditions on the inhabitants’ behaviour in dwellings with mechanical ventilation. In: 7 th AIC Conference, Occupant interaction with ventilation systems. Stratford-upon-Avon, UK, 29 September – 2 October 1986.

Fox, J., 2008. A Study of occupant controlled ventilation within UK dwellings. PhD. University College London.

Garland, et al., 1993. Residential Energy Usage and the influence of occupant behaviour, Proceedings of the ASME Winter Annual Meeting, New Orleans, Louisiana, The American Society of Mechanical Engineers.

Jacobs, et al., 2010. Window opening in High Performance Buildings. Department of Energy & Comfort Systems.

Shipworth, M., 2011. Thermostat settings in English Houses: No evidence of change between 1984 and 2007. Building and Environment, 46(3), pp. 635-642.

Van Dongen & Phaff., 1989. Ventilation behaviour & indoor air problems in different types of newly built dwellings. Environmental International, 15, pp. 95-106.

Van Dongen, 1986. Inhabitant behaviour with respect to ventilation. Occupant interaction with ventilation systems. Stratford-upon-Avon, UK, 29 September – 2 October 1986.

Wallace, et al., 2002. Continuous measurements of air change rates in an occupied house for 1 year: The effect of temperature, wind, fans, and windows. Journal of Exposure Analysis and Environmental Epidemiology,12, pp.296-306.

Wouters & De Baets.,1986. A detailed statistical analysis of window use and its effect on the ventilation rate in 2400 belgian social houses. In: 7th AIC Conference, Occupant interaction with ventilation systems. Stratford-upon-Avon,UK, 29 September – 2 October 1986.

THANK YOU!THANK YOU!

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