All New Zealand houses are heated by the sun to some degree, but some are better at using the sun's heat than others.
Designing your new house to include passive solar design principles will:
Before purchasing a heat pump, ask for advice on the most appropriate size of unit for the area to be heated. Select the pump that is most suitable to prevent excessive operation times or load on the unit.
Choose a heat pump with a low sound power level. The exterior sound power level will be specified on the side of the unit and will give you an indication on how noisy the heat pump will be outside your house. The higher the number the louder the heat pump unit will be. The sound power level is different from the sound pressure level.
The inappropriate location of heat pumps close to, and facing, neighbouring bedrooms and living areas can cause noise disturbance. Before installing a heat pump you should consider the effects noise from the outdoor unit may have on yourself and your neighbours.
Heat pumps should be as far away from your own and your neighbours' bedrooms as possible. The fan unit should face the boundary of the property furthest away from the adjoining residences, not towards windows or outdoor living areas of a neighbouring residence.
Try to avoid mounting the pump on a wall and in particular at a high level, as this can result in unimpeded transmission of noise to neighbouring properties. If possible mount the heat pump at ground level and on a solid base, preferably a concrete pad or block. Use rubber pads between the unit and the base to eliminate vibration.
Ensure that where refrigeration lines pass through walls, they have adequate clearance and insulation. Vibration from within walls can magnify noise levels beyond acceptable levels.
Make use of fences and walls between you and your neighbour's home as these can help reduce the transmission of noise. If a nuisance eventuates, you may need to investigate other options such as acoustic barriers or acoustic treatment.
Tonal type sounds, or sounds with a narrow frequency range, are common from rotating parts in units, such as fans and motors. These noises can greatly increase if you do not maintain your heat pump regularly to replace worn bearings or limited life parts before they fail. Loose screws in a metal casing are a common source of buzzing or rattling noises.
When you have your pump installed, ask the installer to provide you with an appropriate maintenance schedule.
There are three key principles to consider when designing your house to utilise the sun's energy:
Position your building so it is orientated to use the sun (eg have the main living areas facing the northern sun, place morning rooms such as the kitchen to the east, and have rooms needing less sun on the southern side).
Have larger windows on the northern sunny side to let the sun's heat into the house, smaller windows on the southern side to reduce heat losses.
Use shading to reduce overheating from the northern and western (afternoon sun) windows in summer, while still allowing the winter sun in.
Once you have the sun streaming in through your northern facing windows, you need to store that heat. This requires using materials that create thermal mass.
Heavyweight materials such as concrete, terracotta and ceramic tiles, brick, mud or clay, all have inherent thermal mass. When exposed to direct sunlight during the day, these materials will slowly warm up and store the heat during the day, then slowly release that heat during the evening.
Thermal mass works best where the floors and walls receive direct sunlight (eg having a concrete slab floor, with tile finish, in north facing windowed rooms).
Thermal mass walls must be insulated on their outside surface, to stop the heat escaping (the trick is to allow the sun to heat the wall inside the heat trap created by the insulation).
Carpet and textile flooring reduce the ability of the mass to absorb heat, so should be restricted to areas not being used for thermal heat storage.
The total area of northern windows needs to be balanced with the amount of mass available to absorb the heat (eg. too much mass or too little solar admittance can make a house difficult to warm up).
The sun is streaming in, warming your north-facing living room with its thermal walls and floors. Now you need to make sure that heat isn't lost back outside when the day cools.
You need to insulate all your exterior surfaces - under the floor, outside walls, roof and windows - to reduce heat loss.
The NZ Building code specifies only the minimum level of insulation required. More is usually better, resulting in a warmer more comfortable home and lower energy bills (eg. doubling the insulation will halve the building's lifetime energy costs. Instead of needing an expensive wood burner, all you may need are a few cheaper electric heaters).
Insulate your windows using double glazing or properly fitted heavy curtains. Double glazing will reduce heat loss through windows by nearly 50% in winter, as well as reducing noise and condensation.
Most architects should be able to design for these basic passive thermal principles. Many can go a step further.
There are many 'environmentally friendly' construction materials and products on the market that you may wish to consider.
Alternative energy options, like solar panels, solar water heating, wind or hydro, can save on electricity bills.
Having a well designed, energy efficient house will mean you should NOT need to install a large heating system like a fire or wood burner, as small controlled appliances are probably all you will need.
The cost of adding passive solar design into a home is highly variable, depending on the size of house, construction materials, site variables, and many other factors. The factors will affect the payback period. However, in general, over an average house life of 80 years, the additional cost will be saved many times over.
Passive solar design is easiest, and cheapest, to incorporate during new construction. However, some measures to increase thermal performance (such as increasing insulation) can be retrofitted to most buildings.
If only the economic cost of some thermal measures (eg. double glazing) are compared to other traditional methods, the cost can be quite high. However, the potential energy savings and other benefits that may also result (eg. warmth, less condensation, noise reduction) should be included as part of the cost-effectiveness assessment.
To find out more visit Energy Efficiency and Conservation Authorities website.