10 pointers towards more sustainable buildings
If funds are limited, build or refurbish to current Building Regulations and think carefully about the following.
If you want to go further then think about the following 10 points to more sustainable buildings.
This is the starting point. Think thickuse about 300 mm of insulation all round in the roof, walls and floor. Make sure the insulation material has a zero ozone depletion potential (ZODP)
Make sure the windows are not a weak link in the fabric insulation. Consider double or triple glazing with low emissivity coatings and gas filling. Avoid PVC frames.
Take care to eliminate thermal bridges in the insulation. This is particularly important at the junctions between walls, roofs and floors and around openings. Also bridging in the structure needs attention: timber studs, metal wall ties, blockwork returns can all reduce the effectiveness of the insulation.
There is no point in having lots of insulation if air can leak through the structure. Take a strategic view of how air leakage is to be avoided. Design airtight details. Use a pressure test to ensure the strategy has been carried through on site.
In an airtight construction it is important to supply air where it is needed when it is needed. Use a system that supplies and extracts air such as Passive Stack Ventilation (PSV), assisted PSV (both using humidity controlled inlet and exhaust grilles) or heat recovery ventilation (HRV). HRV is the most efficient but to be a net benefit the heat exchanger needs to be over 70% efficient and the fan power needs to be less than 2 W per litre/sec of extract air (you can do better than this). Also the unit and all the ductwork should be kept within the insulated / airtight shell.
Take great care to provide good daylight conditions in all habitable rooms. Use energy efficient lighting throughout. Usededicated' compact fluorescent lamps which cannot be swapped for inefficient tungsten lamps.
Consider ways of eliminating the need for electrical appliances. Provide a clothes' drying space, provide a cold room for food storage. Use only A-rated appliances (or A++ for fridges and freezers). Look carefully at the stand-by losses of all appliances especially TVs, videos, computers, cookers.
Choose appropriate paints and finishes (considernatural' ormineral' paints; otherwise low-VOCsynthetic'), coupled with a good ventilation system, to ensure a fresh environment. Use floorboards in preference to carpets.
Don't get too hung up on the energy used to produce the building materials. Usually it is not significant in terms of the energy used to run the building. But keep an eye on transport energy particularly when dealing with heavy materials such as masonry.
If the load reduction measures have been addressed, then it makes sense to consider renewable energy systems. Biomass (logs, wood chips, wood pellets) can be used for heating and hot water. A small wind turbine is likely to be more cost effective for providing electricity than photovoltaic (PV) panels. Solar panels can be used to provide about half the hot water needs. All the systems need good controls.
www.aecb.net – The Association for Environment Conscious Building
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