Building an energy efficient house: the 10 best tips

1. Choose an architect who understands energy efficient home design

• Make sure builders are aware of your home’s low energy goal
• Choose dealers who have knowledge and experience in energy efficiency
• Remember that many architects/builders do not go beyond the minimum building rules and regulations, but the minimum is not the most efficient.

Minimize your heat loss:

• Keep your house plan simple and compact: A compact house with no extensions will have less heat loss due to reduced external wall and roof area. Remember that one-story houses such as bungalows lose more heat through the roof than two- or three-story houses where rising heat is harnessed on all levels before reaching the roof.
• External walls must have high level insulation
• Make sure there is good controlled ventilation and protection from drafts.
• Your architect can provide you with energy calculations of expected annual fuel bills

Maximize your solar heat gain:

• Build along the east-west axis – an energy efficient home will capture 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 protected from prevailing winds.
• Houses in the northern hemisphere should place most windows on the south side with a 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 need to be on the non-sun side to allow good natural light into all rooms of your home.
• Kitchens and breakfast rooms are mostly used in the mornings, so for homes in the northern hemisphere, a southeast orientation will take advantage of the morning sun. For houses in the southern hemisphere, a northeast orientation will take advantage of the morning sun.
• Hallways, stairwells, and bathrooms can be located on the side that doesn’t get a lot of sun, since they are used less frequently.
• Locate living rooms and master bedrooms on the sun-facing side
• In two-story homes, 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 the floor above warms.
• Use the energy of the sun
  • Wind turbines can make the most of wind power generation
  • Heat pumps use energy from the sun: all renewable energy systems are complementary to an energy efficient home design.

Install an efficient heating and hot water system:

• renewable energy systems
• Solar heaters
• Use a condensing boiler if you use gas or oil
• Install easy-to-use controls

More information about these can be found on the Home Heating Systems and Solutions site.

Consider the thermal mass

• When thinking about an energy efficient home, remember that the use of certain materials will also improve the ‘thermal mass’ of your home through its ability to slowly absorb solar heat during the day and then slowly release this free heat at night – Materials Common uses 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 – Capable of storing a large amount of heat over a long period of time like heat bricks in a sauna.
  • High density – basically the weight (mass) of a material in relation to its volume (its 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 a high thermal mass because it can store a lot of heat). Insulation materials have lower thermal conductivity to restrict heat flow and absorption.

isolation

• The percentage of heat loss from a house is approximately:
  • 42% ceiling
  • 12%windows
  • 12% Unblocked chimneys and drafts around doors
  • 24% walls
  • 10% floor
• So when you think about building an energy efficient home, understand that installing insulation at the construction stage is the easiest and cheapest way to improve the energy efficiency of your home.
  • You can enhance standard timber framed walls by using 140mm studs instead of 90mm studs; this will allow you greater insulation. Masonry cavity walls can be enhanced by filling with insulating polystyrene foam and using lightweight heat blocks.
  • You must have at least 250mm of loft insulation, 100mm of insulation between the joists and 150mm of insulation on top. Loft conversions require careful attention, especially if dormer windows are fitted, but a high level of insulation can still be achieved.
  • The heat loss from the ground varies depending on the type of ground. However, the insulation of the ground floor is quite easy. Typically a 125mm polystyrene layer/sheet is used. This size will be increased if underfloor heating is installed to minimize heat loss.
  • Make sure the insulation overlaps between items, for example, between the wall and the loft/roof cavity
  • Make sure air gaps, such as wall cavities, are free of debris that could be salvaged and thus compromise the insulating air gap.
  • Make sure fiber insulating materials are not compressed (packed tightly), as this will undermine their ability to properly insulate
  • Make sure all insulating materials are kept dry.
  • Be sure to seal all holes where utilities like water and gas lines enter your home.

Windows And Conservatories

• You will always lose more heat through the windows than through the walls, especially single-pane windows. To minimize heat loss through windows, ‘Low-E’ coated double glazing should be installed in all new houses.
• Double glazing not only reduces heat loss but also offers some sound insulation. With double glazing, the two panes are usually vacuum sealed. However, you can get argon-filled (gas-filled) and triple-glazed units which are worth considering if you can afford them.
• Conservatories can save you some energy by acting as a buffer between the adjoining wall by trapping heat from the sun, thus reducing heat loss from the room separated by the adjoining wall. To be effective, greenhouses should be located on the sun-facing side of the house, and preferably not shaded by trees or other buildings.
• Properly placed greenhouses should not require permanent heating, but the doors separating the house from the greenhouse should be double glazed and closed when not in use.

Efficient home heating

• A well-insulated home is a low-energy home, which means that the heating requirements of an energy-efficient home are lower than those of a similar-sized home that is poorly insulated.
• Your heating system must take into account:
  • Fuel source and availability
  • The time you will spend at home: fast or slow response systems
  • Construction material: houses with a wood frame must have sensible heating, such as radiators or air heat pumps, since wood retains less heat than concrete, for example.
  • Underfloor heating systems are not suitable for houses built with lightweight building materials, such as wooden frames, due to their slower heating response.
• You can have hydronic (wet or water) underfloor heating systems combined with radiators. These are generally designed with the underfloor heating on the ground floor and the radiators located upstairs.
• Solid tile floors work best with underfloor heating. If you prefer a smoother floor finish over tile, you should consider rugs over carpeting for better heat transfer/exit within the room.
• Renewable energy systems, such as heat pumps and solar heating, are perfectly suited to energy efficient home designs.

Ventilation

• Ventilation is an important aspect that should not be overlooked as it provides fresh air and removes stale air and humidity. Moisture removal prevents bacterial growth, thus maintaining a healthy living environment.
• Kitchens should have extractor fans or Passive Stack Ventilation (PSV). The PSV works on the principle that warm air “rises” and carries stale air up and out.
• Mechanical ventilation systems with heat recovery offer filtered air and reduced noise intrusion as windows can be kept closed. However, unless you’re using a renewable energy system, such as photovoltaics (PV) or wind turbines, the power required to run the fans is ruled out as a feature of an energy-efficient home. Also, for a heat recovery system to work efficiently, the house must be well sealed.
• All rooms must have drip ventilation, which allows air to enter at a drip rate to provide the room air change rate per hour (ACH).

lighting and appliances

• These should be rated low energy (low power), saving you money in running costs and helping the planet by reducing CO₂ transmissions

So now you can save the planet and save running costs by building an energy efficient home.