Chris Sanders - Thermal Efficiency and Indoor Air ... - Historic Scotland
Chris Sanders - Thermal Efficiency and Indoor Air ... - Historic Scotland
Chris Sanders - Thermal Efficiency and Indoor Air ... - Historic Scotland
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Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
<strong>Indoor</strong> <strong>Air</strong> Quality <strong>and</strong> Energy<br />
or<br />
Why do we need to ventilate houses?<br />
<strong>Chris</strong> <strong>S<strong>and</strong>ers</strong><br />
Glasgow Caledonian University
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
3 bedroom semi-detached house with solid walls,<br />
no insulation <strong>and</strong> single glazing
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Components of heat loss - Uninsulated<br />
U wall = 2.1<br />
U roof = 2.2<br />
U floor = 0.6<br />
N = 1 ach<br />
T i = 20C T e = 0C
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Components of heat loss - insulated<br />
U wall = 2.1<br />
U roof = 2.2<br />
U floor = 0.6<br />
N = 1 ach<br />
T i = 20C T e = 0C<br />
U wall = 0.40<br />
U roof = 0.16<br />
U floor = 0.25<br />
N = 1 ach
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Walls lined<br />
Chimneys removed<br />
Floors sealed<br />
Secondary glazing<br />
Ventilation rate??
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
If we reduce ventilation in houses will<br />
there be problems?<br />
Why do we need to ventilate houses?<br />
Human respiration<br />
Removing pollutants<br />
Providing air for combustion appliances
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
2007 Domestic Technical H<strong>and</strong>book
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
AD F 2006 Appendix A<br />
Performance Criteria for Dwellings<br />
No visible mould on external walls<br />
NO 2 levels should not exceed specified<br />
values for 1 hour average or long term<br />
average<br />
CO levels should not exceed levels specified<br />
for various exposure times<br />
TVOC should not specified level averaged<br />
over 8 hours<br />
Bio-effluents controlled with air supply rate of<br />
3.5 l/s/person
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Human Respiration<br />
<strong>Air</strong> supply needed to prevent CO 2 concentration rising<br />
above 5000ppm (CIBSE Guide B2)<br />
Resulting ventilation rate in a 280m 3 house with four<br />
occupants
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Bio-effluents (Body odour)<br />
ASHRAE recommends 3.5 l/s/person<br />
With 4 people in a house with volume<br />
280m 3 , this translates to a ventilation<br />
rate of 0.18 ach
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Nitrogen Dioxide<br />
Given typical production rates from gas cooking <strong>and</strong> a<br />
background ventilation rate of 0.5 ach, an extract rate of 2.2 ach<br />
or 12 l/s in a 20m 3 kitchen is required to keep below the limit
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Carbon Monoxide<br />
The levels of CO produced from gas cookers will be controlled<br />
by the same ventilation as for NO 2<br />
CO produced from faulty combustion appliances should be<br />
addressed by proper maintenance <strong>and</strong> fitting CO detectors
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Total Volatile Organic Compounds<br />
Difficult to specify the necessary ventilation rate as<br />
sources vary from house to house
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Water vapour<br />
Learning from Canada<br />
Canada Mortgage <strong>and</strong> Housing Corporation (CMHC) <strong>and</strong> Health Canada advise<br />
controlling humidity in the home by maintaining a relative humidity of between 40 <strong>and</strong><br />
60 percent to limit condensation problems to avoid mould growth.<br />
The National Building Code requires heating-season mechanical ventilation in new<br />
residential buildings because “airtight houses can no longer rely on natural air leakage<br />
through the building envelope for winter ventilation” where reduced air change rates<br />
may be insufficient to provide adequate indoor air quality <strong>and</strong> could lead to<br />
condensation problems. They identify electrically heated houses as being at greatest<br />
risk because, unlike fuel-fired systems, they require neither the replacement of air or<br />
chimneys, <strong>and</strong> consequently tend to experience high humidity levels, interior surface<br />
moulds <strong>and</strong> interstitial condensation.<br />
Linda Sheridan 2008
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Condensation
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Interstitial<br />
Condensation<br />
Problems if structure<br />
not correctly detailed
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Mould Growth<br />
9.8%<br />
1.4%<br />
3.5%<br />
1996 EHCS
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Dust Mites commoner in mattresses<br />
furnishing, carpets etc. when humidity higher<br />
faecal capsules major source of allergens
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health
20<br />
18<br />
16<br />
14<br />
12<br />
10<br />
8<br />
6<br />
4<br />
2<br />
0<br />
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Global burden of asthma<br />
% of children with clinical asthma .<br />
Scotl<strong>and</strong><br />
Jersey<br />
Guernsey<br />
Wales<br />
Isle of Man<br />
Engl<strong>and</strong><br />
New Zeal<strong>and</strong><br />
Australia<br />
Irel<strong>and</strong><br />
Canada<br />
Brazil<br />
USA<br />
Finl<strong>and</strong><br />
Germany<br />
France<br />
Norway<br />
Japan<br />
Sweden<br />
Belgium<br />
Austria<br />
Spain<br />
Saudi Arabia<br />
Argentina<br />
Iran<br />
Estonia<br />
Portugal<br />
Italy<br />
Denmark<br />
Switzerl<strong>and</strong><br />
Russia<br />
China<br />
Greece<br />
Romania<br />
Albania
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Mould has health impacts<br />
45<br />
40<br />
No Mould<br />
With Mould<br />
35<br />
% with asthma<br />
30<br />
25<br />
20<br />
15<br />
10<br />
5<br />
0<br />
No Smokers<br />
Smokers<br />
1996 EHCS
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Sources of water vapour in housing<br />
Overall 10 – 15 kg/day<br />
Aquaria, saunas, whirlpool baths, storage of<br />
green firewood?
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Moisture release from fuels<br />
A 4.5 kW flueless fire used for 8 hours a day will add<br />
5.4kg of water vapour to the atmosphere of the house
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Flueless gas fires<br />
‘Flueless fires are a great way to make a real<br />
contribution towards reducing your CO ²<br />
emissions, which contribute to climate change.<br />
And not only is this type of fire 100% efficient, it<br />
can reduce your fuel bills.’
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
MOULD <strong>and</strong> CONDENSATION<br />
In housing:<br />
Absorbent surfaces<br />
Mould at RH>80%<br />
Health Problems<br />
Metal cladding<br />
Non absorbent surfaces<br />
Condensation RH=100%<br />
Dripping?
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Psychometric Chart
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Design to avoid mould growth constrains temperatures
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Design to avoid mould growth constrains<br />
vapour pressure
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Mould starts on thermal bridges
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Effect of Internal Insulation<br />
T i =20C T e = 0C
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
T i = 20C RH i = 50% T e = 0C
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Ventilation needed to avoid mould growth<br />
on an acceptable thermal bridge: f = 0.75<br />
100<br />
Ti = 20C Te = 5C<br />
90<br />
Mould Growth<br />
Surface Relative Humidity : %<br />
80<br />
70<br />
60<br />
50<br />
40<br />
5 kg/day<br />
10 kg/day<br />
15 kg/day<br />
30<br />
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1<br />
Ventilation rate : ach
100<br />
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Ventilation needed to avoid mould growth<br />
on a severe thermal bridge: f = 0.50<br />
Ti = 20C Te = 5C<br />
90<br />
Mould Growth<br />
Surface Relative Humidity : %<br />
80<br />
70<br />
60<br />
50<br />
40<br />
5 kg/day<br />
10 kg/day<br />
15 kg/day<br />
30<br />
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1<br />
Ventilation rate : ach
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Ventilation needed to avoid mould growth<br />
on a minimal thermal bridge: f = 0.9<br />
100<br />
Ti = 20C Te = 5C<br />
90<br />
Mould Growth<br />
Surface Relative Humidity : %<br />
80<br />
70<br />
60<br />
50<br />
40<br />
5 kg/day<br />
10 kg/day<br />
15 kg/day<br />
30<br />
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1<br />
Ventilation rate : ach
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
The concentration of water vapour outside is<br />
not zero <strong>and</strong> varies significantly over the year<br />
2.0<br />
Vapour Pressure : kPa<br />
1.8<br />
1.6<br />
1.4<br />
1.2<br />
1.0<br />
0.8<br />
0.6<br />
95 Percentile<br />
Mean<br />
5 Percentile<br />
0.4<br />
0.2<br />
0.0<br />
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec<br />
Turnhouse 1983 - 2002
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Much water vapour production is<br />
intermittent <strong>and</strong> localised<br />
2.4<br />
2.2<br />
Kitchen<br />
Bedroom<br />
Vapour Pressure : kPa<br />
2.0<br />
1.8<br />
1.6<br />
1.4<br />
1.2<br />
1.0<br />
0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21<br />
Time
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Moisture in the air interacts with building fabric <strong>and</strong><br />
furnishings – indoor humidity variations can be<br />
controlled by modifications to the surface properties<br />
KU Leuven 2006
Centre for Research on <strong>Indoor</strong> Climate <strong>and</strong> Health<br />
Conclusions<br />
<br />
<br />
<br />
<br />
We need ventilation to remove pollutants<br />
from housing<br />
In a typical house the most important<br />
pollutant is water vapour which causes<br />
mould growth<br />
Problems are likely at ventilation rates less<br />
than 0.5 ach<br />
Get the ventilation right for water vapour<br />
<strong>and</strong> it will be adequate for everything else.
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