Careful planning can decrease the amount of energy consumption of an off-grid building — a key issue if you don’t want to maintain a shed full of batteries. A house built with energy efficiency in mind can consume as little as a tenth of the average grid connected house! Here are things to consider:
Most attention should be given to the ‘thermal envelope’: walls, windows and anything that separates the interior from exterior. First, insulate the walls of the foundation as well as the living space. This can be done by incorporating a combination of plywood and either foamboard or concrete into the main walls. Or you can use thermally-efficient building materials such as blocks made of a lightweight but durable recycled wood particle concrete, reinforced with steel bars – they’ll provide a structural wall system that increases the insulation level.
For the floors, rigid board insulation is the best option: placed under the concrete slab, this high-performance, waterproof insulation helps raise the temperature of the floor slab. It loses up to 75% less heat through the slab than conventional construction.
Windows need to be well sealed and carefully orientated — houses lose around 25% of their heat through the windows. In cold countries, most windows should be on the south-facing wall to capture as much solar energy as possible, the opposite in hot countries. Also, skylights are a good way to reduce the need for artificial light and save electricity.
Heat-producing appliances such as fridges and water heaters — make sure you get energy-efficient ones — should be located in the basement, so that the heat is not lost and can diffuse upwards through the house.
To recycle heat, you can also install a heat recovery ventilator. This device recovers 70 per cent of the heat from stale indoor air while providing a continuous supply of fresh air to the home.
These first steps should dramatically reduce heating and cooling needs of the house and save a lot of energy. An energy efficient home will also be more comfortable that other houses, as the temperature is be more stable, drafts are reduced and humidity is better controlled.
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