Home Ventilation, why do it?
Quite often in a home, you want to maintain a pleasant temperature, usually around 23 to 24 degrees - not too cold nor not too hot. This is often achieved by first stopping the external temperature from interacting with the internal temperature, usually by closing all the doors and windows. Then secondly by applying some form of temperature control to the internal space - so ensuring the temperature is in your personal 'Goldilocks zone' of comfort.
Now, all this closing of doors and windows is all well and good for the temperature but comfort in a building is effected by several other factors, that can be negatively impacted by the attempt to fix the internal temperature. Ventilation is a process by which we 'balance' these other factors to create a much better living environment
in the property. We shall now look at each of these other factors in turn.
1. Internal humidity
Once you close all the doors and windows, it is usual for the humidity
in the house to climb. This is due to us (humans) breathing out humid air combined with the actions of washing clothes, cooking food, having showers, etc. This humidity will then cause secondary problems ranging from the simple condensation on windows, all the way through to mould
and floor boards warping - either a health concern or an expensive fix. So you will need some mechanism to deal with this increasing humidity, yet maintaining the temperature.
2. Oxygen / Co2 levels
With the house being so closed up, you can also get a change in the balance of Oxygen and Co2 in the house - so making it more 'stuffy' to breath in. This is an issue for asthmatics who will be effected first well before anyone else.
3. Allergens & Dust
Air consists of many free floating bits of 'stuff' - this can range from skin flakes all the way through to pollen and chemicals in vapor form. These allergens will often accumulate within a closed house as they will often 'fall out' onto the surfaces in the house as the air is quite often still (compared to the outside). Again this can effect asthmatics rather badly if left unchecked.
To fix these problems, and control the temperature, you need some form of home ventilation system.
Home Ventilation Systems, options available
Home ventilation systems fall into roughly two main groups - those which are 'powered' and those which are not. The first group require some mechanically powered component (usually a fan) to achieve the required ventilation. The second group are designed to not require any additional power source to ventilate. These are termed respectively active and passive ventilation
Passive Home Ventilation
Passive ventilation systems work by making use of either:
- an existing or created 'heat gradient' in a house to expel air, or;
- the topology of the plot the house is on with natural winds to 'blow' through the house.
This form of ventilation is considered an aspect of passive house
design. Note: This form of ventilation will not do anything to 'filter' the air, rather they help avoid the accumulation of bad 'deposits' in the house by keeping the air moving.
Active Home Ventilation
Active ventilation often uses a powered fan to either push air into the house or suck air out of the house - both have the same end result in making the air be changed with the outside.
Now, given that there is a fan employed, you can 'play' around with where that fan is deployed and to where the air is 'sent' to get additional benefits. For instance a roof or attic based fan combined with an air filter allows one to use the warmer air in the roof in Winter to provide heating to your house whilst changing the air for cleaner air. the other benefit with this approach is you get what is termed 'positive pressure ventilation', i.e. the pressure is higher in the house than outside, so 'unclean' air from outside cannot get into the property.
Where the air is sourced from?
The other option with home ventilation systems is exactly 'where' the air that enters the house is coming from. This is usually either from the roof space or from a vent placed in a wall. The wall vent usually is not as filtered as the air taken from the roof, as the roof space will contain dust and particles from the roof insulation - which can be quite allergy causing. Of course this means the benefit with the roof air being filtered is that it can often be cleaner than the air outside!