Building Ventilation Techniques
Ventilation is the movement of air from the outside to the inside of a structure. Ventilation air is the term used for acceptable indoor air quality. Ventilation air is more often than not delivered within the structure by means of mechanical systems that can also humidify, dehumidify, heat and cool the whole structure.When designing a house, natural ventilation is an important aspect. A large percentage of homes in the topics are architecturally designed for natural ventilation. The orientation of homes in the tropics has bedrooms facing either north or south for minimal sunlight. Installing big windows at angled walls or facing walls ensures through ventilation that would keep the bedrooms cool and breezy.
In the temperate zones such natural ventilation can also be achieved by stack ventilation. Stack ventilation works on the principle of the chimney effect. It is the movement of air into and out the building through the chimney, and flue gas stacks. The stack effect helps in naturally ventilating a building by infiltration. What then is infiltration? Since most buildings are not as airtight as the designer wants it to be, heated air comes in from the lowest part of the building and then is sucked up to vents and other openings at the top. The rising warm air reduces the pressure in the building thereby forcing cooler air to "infiltrate" through windows and other openings and leakages. The through ventilation in tropical homes is also a form of air infiltration. It is not uncommon to see whole walls missing in indigenous tropical homes to achieve cooler indoor air.
Is your home properly ventilated?
Having a heating and cooling system in your house do not necessarily mean you have a more than acceptable ventilating system. An acceptable ventilation system is necessary to ensure a healthy, safe and comfortable home. Some signs of inadequate ventilation are condensations on windows, stuffy air and stale odour. Improper ventilation can cause:
- asthma and allergies
- mould growth which could cause damage to life and property
- uncomfortable humidity level
- irritating odours
Excessive home moisture can cause house paints to peel, insects to thrive and wood to rot. Proper ventilation could minimize these if not totally eliminate these problems.
What are the types of building ventilating systems?
There are two basic systems of ventilation: forced-air ventilation and natural ventilation. Infiltration is not really a system per se but more of an accidental natural or stack ventilation.
- Force-air or mechanical ventilation uses an air handling unit (AHU) which is actually a part of the HVAC (heating, ventilating, and air-conditioning) system to directly inject air to a space in your house. The system will blow dry air into your house through the ceiling from the roof space above it. This system would work best when there is an ample amount of space in the roof. Localized exhaust fan can also be placed in strategic places to help circulate air and eject stale air through it.
- Natural Ventilation is applied to homes and structures that were designed accordingly. A good architect and house designer should incorporate acceptable if not excellent natural ventilation to an architectural plan. Natural ventilation is basically opening well-designed and strategically placed window and openings to make air circulate. It can also be achieved by designing an efficient stackable house.
A passive stack ventilation system is currently being introduced in the UK. The system ventilates the entire house by extracting wet air from such areas as the kitchen and bathrooms then ejecting them out through vertical ducts ending up in roof terminals. The difference in the wind pressure causes the moist air to be pulled up the ducts to be replaced by fresh air through vents in the walls or through open windows. Thus fresh air is circulated in the whole house.
Infiltration is not ventilation but it is also used for ventilation air
Heat-exchanger ventilation system basically extracts damp and warm air from living areas then removes the heat by means of a heat exchanger. The heat is transferred to the cold dry air outside then pumped right back into the house. Two advantages of the system are:
It meets the building code requirements for ventilation which is 20 CFM (9.2 L/s) per person in an office and 15 CFM (7.1 L/s) per person for schools. Residential unit requirement is set at 10 CFM, acronym for cubic feet per minute.
These heat-exchanger systems have two advantages. They run all the time, regardless of air temperature in the roof. And they fully meet the building code's requirements for ventilation with outside air. But a properly designed heat-exchanger system for your house can be quite expensive.
It is the thrust of green architects and builders to maximize natural ventilation to help cut energy and cost. A lot of homes and different structures are designed to achieve sustainability.
In order to properly ventilate your home, one of the better ideas is to ventilate your roof by ventilating your attic and crawl space. The heat generated from the hot roof in the summer is enough to make a dent in your energy cost. The hotter the ceiling, the more you'd adjust your cooling system on high and the more your energy consumption will be.
For a regular DIY ventilating the attic is easy enough. All you have to do is make vent through the attic, add an exhaust fan and a thermostat. Make sure that the vent is secure from bats and squirrels. The solution sounds easy enough but if you are in doubt better look for professional help in ventilating your attic.
There are ways and means to ventilate your home. The cost depends on the amount of work needed. The best solution, if you are just about to build your house, is to design your house in accordance to natural ventilation.