and its importance in the home

Energy transference by ventilation

VENTILATION

From September until May it is necessary to add energy to the air in a building in the UK. This is in order to make the building comfortable to the occupants. The quantity of energy, Q, required is determined by three key variables

• the mass of air involved, m
• the specific heat of air, s
• the temperature rise of the air, (T_IN - T_OUT) where _IN & _OUT refer to indoor and outdoor

Q = m x s x (T_IN - T_OUT)

The air in a building is continually being replaced as a result of ventilation and draughts. The impact on heating costs is demonstrated clearly in draughtproofing later. From a heat loss viewpoint, the minimum loss occurs with the minimum ventilation. However there are other considerations - Stale Air, Odours and Condensation:

Stale air :Because of metabolic processes, humans require a specific minimum air flow per room occupant to replenish O₂ that has been consumed and remove the exhaled CO₂

Odour removal :Heating and ventilatilation good practice requires a specific minimum air flow per room occupant.

Condensation prevention :Moisture in humid air, if cooled below its dew point, will condense. Mould growth will occur where this happens particularly at cold surfaces. Sometimes it is necessary to partially dehumidify the air or promote larger air flows or warmer temperatures (to reduce relative humidity) to prevent this.