Low Energy House - Low Energy Technology
The basis of low energy house design is to take advantage of as much zero and low energy technology as possible in order to reduce the need for traditional building technology which is inefficient or consumes a lot of fossil fuel energy in use
Passive Solar Design
A low energy house will be designed so that the south facing windows absorb energy from the sun and the entire building is planned so that this energy can be distributed internally from the south façade. Close attention will be paid to the site and location of the building, the prevailing climate, the design and construction, the solar orientation, the positioning of glazing and shading elements and the incorporation of thermal mass.
Thermal mass allows a body of dense construction materials: concrete, stone, brick etc, to store heat. During the day, when external temperatures are high, a large thermal mass inside the insulated envelope will absorb heat. When the external temperature cools down in the evening, the thermal mass will radiate that absorbed heat into the rooms. In zero energy houses, rammed earth can be used. Earth sheltering around homes can also provide the same effect.
Many domestic activities within a house involve the use of electrical equipment, such as: refrigerators, freezers, dishwashers, cookers, artificial lights, computers etc. These electrical appliances generate a certain amount of heat and these heat gains can be included in the energy input and will be incorporated when calculating the rest of the heat demand.
Energy Efficient Domestic Electrical Equipment
Low energy house design will demand equipment that is rated Class A (or A+ or A++) under the European energy labeling scheme, for refrigerators, freezers, washing machines, dishwashers, driers, ovens, water heaters etc.
Low Energy Technology - Sun Tube Lights
Sun tube lights have been devised to transfer daylight into parts of buildings that have little or no natural lighting. A sun tube light system comprises a skylight, usually situated on the roof, which is connected to a tube which has an internal mirror finish. The tube transfers daylight vertically downwards to illuminate the inside of a building.
Low Energy Technology - Rainwater Harvesting
A rainwater harvesting system can be installed in a house to reduce mains water usage and maintain water supplies in periods of drought. If rainwater is required only for the garden
and car washing, the simplest solution is to connect water butts to existing rainwater pipes. If there is surplus rainwater, it can be used in the home for non-drinking purposes, like flushing toilets
and to fill a washing machine.
Low Energy Technology - Grey Water Collection
Grey water is water that was previously supplied as ‘wholesome water’ but which has been used in washbasins, baths and showers. A typical grey water recycling system collects waste water from baths, showers and washbasins. The water is then treated and stored until it is required for toilet flushing and garden watering.
Low Energy Technology - Autoclaved Aerated Concrete Blocks (AAC)
Probably the most effective insulating concrete blocks available are those manufactured from autoclaved aerated concrete. They are produced to the same dimensions and strength standards as conventional medium and dense blocks. They have the advantage of better thermal insulating properties and are lighter and easier to handle on site.
Most AAC blocks are formed by the addition of aluminium powder to a fine mix of sand, lime and pulverised fuel ash (PFA) and Portland Cement. The inclusion of aluminium filings with concrete mix causes a chemical reaction with the lime during manufacture and gives off hydrogen, producing tiny bubbles throughout the material. Steam curing in an autoclave causes a secondary reaction which gives the concrete blocks increased strength.