- Choose an architect who understands low energy efficient house design
- Be sure that builders are aware of the low energy aim of your house
- Choose tradespeople that have both knowledge and experience in energy efficiency
- Remember many architects/builders don’t go beyond minimum building standards and regulations but minimum isn’t the most efficient.
- Keep your house plan simple and compact – A house that is compact and without extensions will have less heat loss due to the reduction in the external walls and roof area. Remember that single storey houses such as bungalows lose more heat through the roof than two or three storey houses where the rising heat is used throughout the levels before reaching the roof.
- External walls should have high level insulation
- Ensure there is good controlled ventilation and draught-proofing
- Your architect can provide energy calculations of expected annual fuel bills
- Build along the East West axis – An energy efficient house will capture the free energy from the sun to heat your home and water. Ideally where possible choose a site where your house can face the sun (external blinds can prevent overheating in the summer months) and be sheltered from prevailing winds.
- Houses in the northern hemisphere should locate most windows on the south side with reduced window size on the north side, and vice versa for houses in the southern hemisphere – Most windows should face the sun side to benefit from solar gains. However, some windows will have to be on the non-sun side to enable good daylight in all the rooms in your home.
- Kitchens and breakfast rooms are mostly used in the mornings, so for houses in the northern hemisphere a south-east orientation will take advantage of the morning sun. For houses in the southern hemisphere then a north-east orientation will take advantage of the morning sun.
- Halls, stairs and bathrooms can be located on the side that doesn’t get much sun as there are less frequently used.
- Locate living rooms and main bedrooms on the sun facing side
- In two storey houses consider having your bedrooms on the lower level (cooler for sleeping) and your living rooms on the upper level further reducing your heating requirements as upstairs gets warmer
- Use the sun’s energy
- Wind Turbines can take full advantage of wind power generation
- Heat Pumps use the sun’s energy – all renewable energy systems are complementary to an energy efficient house design
- Renewable energy systems
- Solar heaters
- Use a condensing boiler if using gas or oil
- Install easy to use controls
More information on these can be found at the Home Heating Systems and Solutions site.
Consider Thermal Mass
- When thinking of an energy efficient house remember that the use of certain materials will also improve the ‘thermal mass’ of your house by their ability to slowly absorb solar heat during the daytime and then slowly release this free heat through the night – The common materials used for thermal mass are:
- Adobe bricks (mud or earth bricks)
- Rocks and stones
- Concrete (preferably concrete with stone)
This is because they have:
- High specific heat – able to store a large amount of heat for a long period of time like the heat bricks in a sauna
- High density – basically the weight (mass) of a material in relation to it’s volume (it’s size) – the greater the mass per unit volume the greater the density
- Low thermal conductivity – slow absorption and slow release of heat
- Thermal mass is not insulation, it is the amount of specific heat that can be stored in a material (water has high thermal mass by being able to store a lot of heat). Insulation materials have a lower thermal conductivity to restrict the flow and absorption of heat.
- The percentage of heat loss from a house is approximately:
- 42% Roof
- 12% windows
- 12% Unblocked chimneys and draughts around doors
- 24% walls
- 10% Floor
- So when thinking of building an energy efficient house understand that installing insulation at the build stage is the easiest and cheapest way of improving your homes energy efficiency.
- You can upgrade standard timber framed walls by using 140mm studs instead of 90mm studs – this will allow you more insulation. Masonry cavity walls can be improved by being filled with polystyrene insulating foam and by using lightweight thermal blocks.
- You should have at least 250mm of loft insulation, 100mm of insulation between the joists and 150mm of insulation laid across the top. Loft conversions require careful attention especially if dormer windows are installed but a high standard of insulation can still be achieved.
- Heat loss from the floor varies with different floor types. However, ground floor insulation is pretty easy. Generally a 125mm layer/sheet of polystyrene is used this size will be increased if installing underfloor heating to minimize heat loss.
- Ensure insulation overlap between elements, e.g, between the wall and loft/roof cavity
- Ensure air gaps such as wall cavities are clear of debris that can bridge therefore compromising the insulating air gap
- Make sure fibre insulating materials are not compressed (packed tightly) as this will undermine its ability to properly insulate
- Make sure that all insulating materials are kept dry
- Be sure to seal all holes where services such as water and gas pipes enter your home
- You’re always going to lose more heat through windows than through walls especially single pane windows. To minimize heat lost through windows ‘Low-E’ coated double glazing should be installed in all new houses.
- Double glazing does not only reduce heat loss, it also offers some sound insulation. With double glazing the two panes are generally vacuum sealed. However, you can get argon-filled units (gas filled), and triple glazing which are well worth considering if you can afford them.
- Conservatories can save you a little energy by acting as a buffer between the adjoining wall by trapping the heat from the sun, thereby reducing the heat loss from the room separated by the adjoining wall. To be effective, conservatories should be located on the sun facing side of the house and preferably not overshadowed by trees or other buildings.
- Conservatories correctly placed should not require any permanent heating, but the doors that separate the house from the conservatory should be double glazed and shut when not in use.
- A well insulated house is a low energy consuming house meaning that energy efficient house heating requirements are lower than a similar sized house which is poorly insulated.
- Your heating system should take into account:
- Fuel source and availability
- The time you will spend in your home – quick or slow response systems
- Construction material – timber framed houses should have responsive heating, such as radiators or air heat pumps, as the timber retains less heat than concrete, for example
- Underfloor heating systems are not suited for houses built from lightweight construction materials, like timber frame, because of their slower heating response
- You can have hydronic underfloor heating (wet or water based) systems combined with radiators. These are usually designed with the underfloor heating downstairs and radiators located upstairs.
- Tiled solid screed floors work the best with underfloor heating. If you prefer a softer floor finish rather than tiles you should consider rugs rather than fitted carpets for better heat transference/output within the room.
- Renewable energy systems such as heat pumps and solar heating are perfectly suited for energy efficient house designs.
- Ventilation is an important aspect not to be overlooked as it provides both fresh air and removes stale air and moisture. Removing moisture prevents bacterial growth thus maintaining a healthy living environment.
- Kitchens must have extractor fans or passive stack ventilation (PSV). PSV works using the principle of ‘rising’ warm air carrying stale air up and out.
- Mechanical ventilation systems with heat recovery do offer filtered air and a reduction in noise intrusion as windows can be kept closed. However, unless you are using a renewable power system such as photovoltaic (PV) or wind turbines, then the power required to run the fans rules it out as a feature for an energy efficient house. Also, for a heat recovery system to work efficiently the house must be well sealed.
- All rooms should have trickle ventilation – allowing air to come in at a trickle rate to provide required room air change rate per hour (ACH).
- These should be low energy rated (low-wattage) saving you money in running costs and helping the planet by reducing CO2 emissions.
So now you can save the planet and save yourself running costs by building an energy efficient home.
Source by George Meates-Dennis