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Heating & Cooling
Two of the the hottest topics (sorry!) when it comes to healthy and green building and related issues of sustainability and environmental protection.
This is a massive subject area worthy of a website of its own, but let’s make a start …
Our comfort zone, in terms of the optimum temperature within our healthy home, lies roughly between 15 & 25 Degrees Celsius. The exact temperature will vary dependant upon a number of variables including norms for the inhabitants, surface temperatures, air moisture levels, circulation of the air and the nature of any heat emitted in the environment.
Passive solar design is a design approach through which we seek to harness the power of the sun to our advantage for heating a building.
The key concepts to be considered are:
- The strength of the sun at different times of the year.
- Striking the balance between heating and over-heating.
- The technology and building techniques we can use achieve 1 & 2.
More? Passive Solar Design
Good passive solar design [see the infobox to the left] will be essential in designing an effective, sustainable and healthy heating and cooling system.
Heating
The provision of warm surface temperatures is a key to providing healthy green heat. If we are able to heat surfaces rather than the volume of air, then we are able to maintain achieve comfortable levels of heating with a lower and healthier air temperature.
So what is so bad about air heating as opposed to surface heating?
- Warmer air temperatures reduce our ability to concentrate and increase skin moisture levels (sweat / perspiration) and tiredness.
- Warm air heating systems have been linked with transmission of common viruses, increased occurrence of headaches and reduced circulation.
- Warm air heating is inefficient in that as warm air rises, the whole volume of air in a room needs to be warmed, including that above the heads of the occupants to ensure that the warm air reaches down to the occupants.
Lower air temperatures also make essential ventilation less of an issue. The energy loss when ventilating is lessened as the difference between the warmed internal & cooler external air temperatures is likely to be less.
Cooling
At its simplest, cooling of the occupants of a building can be achieved through appropriate positioning of the occupants, provision of opening windows and the employment of fans.
The thermal mass of a room, as defined by the mass of the dense structural elements of the room can be utilised in passively cooling air temperature during the day. Heat will flow from the warm air into the cooler structural elements, reducing air temperature by up to 3 degrees Celsius. The system will need to be ‘reset’ overnight through ventilating the structure with cooler night air - in doing so reducing the temperature of the thermal mass which will provide cooling on the following day and so on…
Garden design can assist in keeping property temperatures in check - carefully placed deciduous trees can block up to 90% of the suns rays in the Summer and even when bare of leaves in the Winter up to 50% or so. Similarly, climbing plants will provide additional shade. A well planted garden will have a cooling effect brought about by transpiration from the leaves of plants.
Mechanical cooling options are extensive, but are difficult to justify on green or sustainable grounds and are thus considered beyond the scope of this site.