Home Energy Use

When looking at the energy use, and associated carbon emissions of homes, we need to consider the energy required for heating & cooling, cooking, hot water, appliances, lighting and electric vehicle charging.

In New Zealand we are lucky that 84% of our electricity currently comes from renewable sources, the 4th highest in the OECD according to MBIE. Home owners can also select a power retailer with plans that ensure 100% of the power is generated from renewable energy.

As the majority of New Zealand’s energy is renewable, a simple way to significantly reduce our carbon emissions is to remove the need for gas within the home. Traditionally gas has been an option in New Zealand for cooking, hot water heating and occasionally heating. With modern cooking options like induction cooktops and energy efficient hot water heat pumps, AM Architects recommend that gas should no longer be connected to new homes. Household appliances can account for 30% of the home energy use, so investing in high efficiency appliances can bring substantial savings to energy, water & money over time and reduce carbon emissions.

Solar Power Generation

Having a solar photovoltaic (PV) system installed is a simple way to reduce the energy use of a home towards carbon neutral. The cost of PV systems has reduced significantly which allows the installation cost to be offset against power costs in a shorter period of time. Excess electricity generated from the PV system can be stored in batteries to bridge gaps where there is insufficient sunlight, at night or on cloudy winter days.

Smart devices are becoming more common in homes and aid in better management of power demand throughout the day/night to minimise reliance on power from the national grid, and maximise power use from on site generation.

Hot Water

Heating of hot water can account for up to a third of a homes power consumption.

Unlike gas-powered hot water systems, energy-efficient heat pumps use no fossil fuels if powered by renewable energy. A hot water heat pump works in a similar way to a reverse cycle air conditioner, but they heat the water instead of the air. The heat pump is installed on the exterior of the building and connects to a highly insulated water tank for storage. This allows for cheap heating of the water during the day at off peak power times, for storage in the morning or evening in the peak hours when power is more expensive. Modern heat pump systems use between 60 and 75% less electricity than conventional hot water cylinders.

As an alternate option, solar hot water systems can be installed on the roof to expose the water to the sun via a series of water filled tubes. An associated electric ‘booster’ system is advised for days when little or no direct sun is exposed to the system.

Heating & Cooling

With good passive design a high performance house will maintain comfortable temperatures throughout most of the year, however additional heating and cooling may be required on very hot or cold days depending on the local climate.

At AM Architects, in the first instance we aim to design out the requirement for air-conditioning to significantly reduce the energy demand. In Auckland, good passive design - combined with ceiling fans that use minimal energy - is generally sufficient for cooling a home in summer.

Reverse-cycle air conditioning, commonly known as heat pumps are popular energy efficient systems that can heat the air in the winter, and cool it in summer. The two commonly used varieties include a ‘split system’, where the heat pump is located outdoors and the wall unit is located indoors, and a ‘ducted system’ where the indoor system is hidden , usually in ceiling spaces and the air is ducted to a series of outlets through the home.

Hydronic heating systems work by pumping hot water (that is heated via a heat pump) through wall mounted units or underfloor piping systems to radiate heat back into the space.

Lighting

Sunlight entering the interior of homes, either directly or diffused provides beautiful natural light that can enhance the feeling of a room. The size and placement of windows, doors and skylights help regulate light throughout the day.

Natural light is supplemented with artificial lighting. LEDs can be used throughout a house to provide an energy efficient, long lasting light source. In conjunction with timers, daylight controls and motion sensors, artificial lighting can be turned on and off automatically to ensure lighting is only provided when required.

Most residential homes we see include excessive numbers of light fixtures, providing overly bright spaces that lack atmosphere. At AM Architects, we design lighting plans to reduce the number of required fittings, while ensuring plentiful light is allowed in task based areas which in turn reduces energy & fitting costs. Floor & bedside lamps can then be added to personalise the space and create added atmosphere.

Water

Water is a precious resource. Specifying water-efficient plumbing fittings reduces water use, and in doing so also reduces energy use as less water is required to be heated. The Water Efficiency Labelling Scheme (WELS) indicates flow rates in litres per second and allows us to easily compare fittings. The higher the star rating, the more efficient the fitting.

In addition to efficient water use, rainwater can be collected from the roof, stored in a tank either next to the home or underground and reused for toilets, the laundry and garden irrigation.

Using stormwater on site also reduces the runoff that enters the public stormwater system. As water runs off from a site, it can carry with it other matter than can pollute our precious waterways. Designing vegetation, and minimising sealed surfaces by using permeable options like stone or brick paving will also reduce the amount of stormwater that leaves the site.