The Importance of Ventilation in Your Home
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If we sealed our home completely, we should only get fresh air inside when we opened a door or window. We need ventilation to exhaust unwanted smells, water vapour and pollution, and replace them with fresh air, but we also need to control ventilation so that we can turn it on and off as we need it, and direct it where it is necessary. In this way we can prevent the waste of heat in the way that water is wasted through dripping taps. We then only lose the heat in air allowed to escape for ventilation purposes.
Conventional wisdom has established that an average-sized room requires at least one air change per hour when occupied. However this varies and is dependent on such factors as the number of occupants and the number and nature of the sources of pollution. Traditionally, ventilation was achieved with the use of air bricks and infiltration; however, as our energy conserving becomes more sophisticated, we need to develop a correspondingly more sophisticated ventilation strategy. Before listing the possible measures in a strategy, we shall look at ventilation for combustion and heat exchangers.
Permanent ventilation for combustion
It is a statutory condition that heating appliances which require air from inside a room for safe operation should have a permanent ventilator. The danger is that the fuel does not burn efficiently without sufficient oxygen; if toxic products of combustion are not exhausted, they can build up in a room and possibly prove fatal. In old houses the original ventilators are often papered over and it is obviously important that either they are unblocked or an alternative route is found for the incoming combustion air. One way of providing this alternative route is via a purpose-built duct delivering air directly to the appliance. Many modern appliances overcome this problem by having a balanced flue which draws air from the outside and expels it through the same fitting.
Heat exchangers
Is there any way we can save the heat lost through controlled ventilation? Heat exchangers are designed to do just this. They are a relatively new method of recovering the heat from warm air before it is exhausted to the outside, and are being used increasingly as part of an overall strategy for ventilation and energy conservation. The principle is simple: the outgoing air is extracted through a matrix of hollow tubes and fins which warm the incoming air contained within them. In larger systems, warm air is collected via ducts from various places around the house, such as bathrooms and kitchens, and the warmed fresh air is delivered to the living rooms. The heat exchanger can be placed anywhere in the house but the roof space is the usual location. Expert advice is essential if you are thinking of installing a heat exchanger.
Your ventilation strategy
Once you have identified individual problems in each room of the house, such as a heater requiring combustion ventilation or a room with too much humidity, it is necessary to draw up a ventilation strategy. Perhaps the most important decision you should make at the very beginning is whether to install a heat exchanger with ducts to various parts of your home. If you decide this then the problem is more or less solved in one go. This should be the most energy-efficient option. If not, consider all the measures below and try to balance the air flow in each room of the house so that you have an inflow and an outflow. If this seems complicated, persevere and find ways of simplifying the problem in your mind: for instance, if you fit controllable trickle ventilators to all your windows, leave gaps round the internal doors and install extractor fans in the bathroom and kitchen, this would be suffi¬cient. You will of course always have the option of simply opening windows as required. It is up to you how sophisticated a system you devise. Remember that in a tall house in very cold or very windy weather, whatever system you have will need to be closed right down as the pressure differences will force air through much smaller openings. Whatever you decide, it is important to develop a ventilation strategy that fits your home the way you use it. These are the possibilities for you to consider:
o Decide whether to install a heat exchange system.
o Fit controllable trickle ventilators in each room to obtain cross ventila¬tion (the ease with which these can be fitted to existing windows varies with the type of window).
Ventilation strategies.
o Install mechanical extractor fans in kitchen and bathroom, controlled by a timer or humidistat (moisture control switch).
o Install permanent ventilation for combustion appliances which rely on a supply of air from inside.
o Use defunct chimneys as channels for ventilation or ducting. This may be particularly useful if it is difficult to fit ventilators to the windows. Consider also using your chimneys to recirculate warm air to upper storeys or vice versa.
o Install air-cleaning measures: either mechanical or biological, ionisers or filters. If the main problem is humidity then consider using a dehumidifier and if lack of humidity then consider a misting humidifier or again the use of plants.
o Opening and closing windows as necessary: if external doors are constantly being used, this may provide sufficient ventilation for much of the day.
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Source by Tauqeer Ul Hassan