2. Draught Finder Trevor Clark Qualified L1 Air Tester & Thermographer
Affiliate Member BINDT
(British Institute of Non Destructive Testing)
Independent Airtightness Testing Scheme
UK Thermography Association

3. Ventilation is very, very important!
12. CONDENSATION
This presentation is intended to provide a brief description of Condensation & it’s affects.
Airtightness is now seen as a fundamental element in the construction of low energy, healthy buildings.
But having an Airtight building can bring unexpected consequences!
Having an Airtight building also means designing & installing sufficient air circulation that brings in fresh air and exhales stale moisture loaded air.
Ventilation is very, very important!

4. CONDENSATION
What is Condensation?
Condensation is the formation of water droplets on a surface that is colder than the moisture laden air around the surface.
Water vapour is held in air until the temperature of the air meets a surface at a lower temperature that corresponds with the ‘Dew Point’
Condensation generally appears in the uppermost external corners of a building (bedrooms) or where the air is still (wardrobes) or where cold surfaces exist (bathroom, kitchen)
Water is a problem in buildings. It helps create the ‘right’ conditions for mould and fungi to grow.
With these spores in your home, health issues can follow. Breathing problems if anyone suffers from Asthma can be exacerbated.

5. CONDENSATION Where does the water come from?
Water vapour is in the air all around us.
It is generated in the home by the way we occupy our homes, in other words by what we do inside our buildings.
Here is a list of how much water is produced per day in an average home:-
Per Bath
0.2 litres
Per Shower
0.3 litres
5 average sized plants
0.4 litres
Cooking (3 Meals)
1.7 litres
Cooking on Gas Stove
1.5 litres
Floor Washing (12m²)
1.8 litres
Drying Clothes - Inside
1.9 litres
7kg clothes tumble dried
9.0 litres
4 Occupants - adults
9.0 litres
Each person expires 2.25 litres by breathing alone.
Any physical activity would increase these figures
Excess Moisture is:
BAD for our health
BAD for our buildings

6. CONDENSATION How can we control Condensation?
Controlling Condensation can be difficult, but a well designed ventilation system can eliminate the problems associated with condensation in buildings.
See our other slide shows:
2. Draughts & Ventilation
10. Available Ventilation Systems
Download the PDF information on these (& other subjects) on the Information Page
Water Vapour will remain in the air as long as the temperature of the air or surrounding surfaces remains above the ‘Dew Point’ Temperature.
When the temperature drops, the Water Vapour cools and condenses to form either:-
Mist
Fog
Rain
or Water Drops on the cooler surface.
As water vapour is lighter that air it will generally float up to the top of the space it occupies, hence being found in the corners of cold rooms.

7. CONDENSATION How can we control Condensation?
To control condensation you need to do one, or more of the following:-
1. Reduce or Eliminate the source of the water vapour.
2. Dry your clothes outside whenever possible and when drying inside is the only option, try and isolate drying to a small room that is well ventilated
3. Avoid drying clothes on radiators as this is a major contribution to condensation.
4. When producing steam in a bathroom or kitchen, make sure you keep the door shut tight to prevent the steam from spreading to the rest of the house.
5. Open a window in your bathroom and kitchen whilst cooking or bathing, to allow the steam to vacate your property.
6. Cover pans when cooking, (This will also save some energy!)
7. Do not block air vents and make sure your furniture and cupboards are not up tight against walls, especially external walls.
8. If you use a tumble drier make sure it's vented correctly, preferably to the outside.
9. Keeping your heating at a low level for a long period of time will gently warm the fabric of the building, reducing the cold surfaces on which warm wet air will condense.

8. CONDENSATION How can we control Condensation?
Generally condensation will form on any surface (wall, ceiling or clothes) because the air is still and the temperature of the surface is below the dew point, in a home with an indoor temperature of 21°C and Relative Humidity at 50% this temperature is approximately 10°C.
If the %RH increases to 80% without the temperature rising, the dew point also increases to approximately 17.5°C - so more condensation.

9. CONDENSATION How can we control Condensation?
If we now reduce the room temperature to 17°C & keep the %RH at 50%, having a cooler internal room air temperature means the surface temperatures will also be lower (wall, ceiling or clothes). Reducing the temperature to 6.5°C will cause condensation to form.
If room temperature remains at 17°C but the %RH is increased to 80% the dew point temperature will increase to 13.5°C - so more condensation.

10. CONDENSATION How can we control Condensation?
It is best to maintain the room temperature around 19 to 21°C and the %RH in the air to between 30% and 60% for Optimum Comfort Conditions.
A good ventilation system with automatic controls will maintain these conditions.
Fans with Humidistat Sensors or Whole House ventilation systems are available.

11. CONDENSATION How can we control Condensation?
Condensation if not tackled can lead on to more serious problems with Mould & Fugal growths.
Unchecked levels of moisture (condensation) and relative humidity combined with a suitable organic breeding place such as wood, carpet, wall paper etc., will inevitably lead to mould growth & fungal growths.
Mildew forms in wall cavities and crevices and microscopic mould spores can be inhaled by humans triggering asthma, allergies and skin disorders.
Spores from certain types of mildew, mould & fungi can cause serious respiratory illnesses.
The Housing Health and Safety Rating System (HHSRS) identifies damp and mould as one of the 24 hazards which could cause 'risk or harm to health and safety of an actual or potential occupier'

12. CONDENSATION
Air Tight Homes
Modern dwellings are designed with increasingly reduced air infiltration rates and higher levels of insulation making them almost completely sealed. Consequently the air inside can become moist, stale and generally stuffy & unpleasant to breathe.
Ventilation is key to the elimination of condensation, the main reason for ventilation is to remove the water vapour from the air inside buildings.

13. Trevor Clark CONDENSATION Qualified Air Tester & Thermographer
If you are experiencing any of the problems in the previous slides, please call TREVOR for an informal discussion on how we can help reduce condensation. Mob:
Trevor Clark
Qualified Air Tester & Thermographer
Thank you for reading …. Check out our other Slide Presentations in this series