Renovations that lower your power bill

Create an energy efficient home while planning your renovation by learning about where to place priorities to achieve maximum energy savings when renovating on a set budget.

Energy efficiency
ARTICLE Dana Alexander PHOTOGRAPHY Homestar

You may not dream of living in the ultimate eco-house, but understanding the causes of wasted energy and thus wasted money when planning your renovation makes sense. Kiwis are confronted with messages about the need to reduce energy consumption on a daily basis but are often confused about where to place priorities to achieve maximum energy savings when renovating on a set budget.
Dana Alexander, business development manager for Homestar says: “Most New Zealand homes are on to three Homestar rated on a scale of ten, meaning they are generally under performing in areas of energy efficiency and warmth. We find that the public often perceives eco and energy efficient homes are expensive, but they don’t have to be. Any extra investments made now generally pay for themselves long-term, so it is extremely important to talk with your building partner about creating a comfortable and long-term cost-efficient home to suit your needs.”
House diagram showing areas to focus on
The average home allots 30 per cent of the household energy bill to heating, a further twelve per cent to electronics, eleven percent to refrigeration, six percent to lighting, and eleven per cent to cooking and other power uses.

Aim to lower your future power bills by focusing on:

  1. Having a fully insulated home
  2. Selecting double-glazed, low-e windows and thermally broken joinery
  3. Selecting an energy efficient heating option
  4. Investing in high-rated energy star appliances
  5. Utilising energy-saving light bulbs and design Insulation

Upgrading your insulation pays for itself over time and continues to save money for the life of the home. The benefit of adequate home insulation is the positive effects it has on the health of the occupants. Homes with an internal temperature below 16°C have an increased risk of respiratory disease. The World Health Organisation recommends houses maintain a minimum temperature of 18°C to ensure occupants remain healthy and comfortable.
Toy model of a home wrapped in a scarf
Depending on the size and specification of the house, upgrading the insulation may only represent a 1 per cent increase in the total build cost but the on-going savings for the homeowner are significant. Since 2005, electricity prices in New Zealand have increased on average 51.4 per cent nationally.
A 2010 BRANZ report showed that on average there was a 17 per cent saving in energy to heat and cool a home when upgraded insulation was installed instead of New Zealand Building Code minimums.
About 35 per cent of heat loss from an average uninsulated house occurs through the ceiling, so insulating roof cavities should be a top priority. In the same uninsulated house 24 per cent of heat is lost through the walls and 20 per cent through the floor.
If extending with a newly built add-on, increasing frame size to fit more insulation in the wall cavities is an option that should be considered for significant energy savings long term.
Or try an easy retrofit solution for insulating underfloor with expanded polystyrene panels, designed to slot between floor joists.
“A well-insulated home will provide year-round comfort as well as reduce the incidence of illness, with research showing that proper insulation leads to reduced occurrences of asthma,” says Dana Alexander.
Double-glazed windows
“It’s also great for reducing noise levels and managing condensation, so the benefits of insulation go far beyond temperature regulation.”
Windows and joinery
Insulation is a key element for all houses, but many homeowners don’t realize its full potential as a result of sub-par windows and joinery.
In order to seal warmth within the home as fully as possible insulation should be paired with double-glazed windows and thermally broken window frames, which prevent metal conducting the cold from outside into a nice warm house.
Ideally all window glass will be low emissivity or ‘low-e’, with a special coating that reflects heat back to its source while letting light through.
This results in extremely efficient windows that redirect heat back inside on cold winter nights and back outside on hot summer days.
If replacing windows or retrofitting a second glaze isn’t an option then thermal-backed curtains are vital to prevent heat escaping through the glass and joinery. Make sure curtains reach the floor and sit snugly against the window for maximum benefit.
Turning on a heat pump
With 30 per cent of household energy bills dedicated to heating, choosing an energy efficient heating source is paramount. If you’re looking to install a new heating system in your home, a heat pump could be your best bet.
They’re quiet, require minimal effort compared to wood or pellet burning heat production, and when used properly are the most efficient option to heat your home.
Make sure before you invest in a heat pump that your home is properly insulated and always use a registered installer.
If designing a new extension you could also take control of the amount of direct sunlight that comes into the home to assist with passive heating and cooling.
The simplest way is to have good sized eaves of at least 600 millimetres, which will allow low-sitting winter sun to stream into your home, while shading against more intense summer sun that sits higher in the sky to keep rooms cool.
Kiwis waste $100 million a year leaving their labour-saving appliances on stand-by, so switch yours off at the wall when you aren’t using them.
Other easy wins in the energy efficiency crusade include using a timer for heated towel rails and the washing line to dry clothes whenever possible, which could save you a combined total of $370 over the course of the year.
A bigger step you can take to reduce energy usage in your home is to replace outmoded appliances for energy efficient ones.
A home fully equipped with Energy Star products uses approximately 30 per cent less energy than a typical house – just imagine saving a third off your power bill every month!
Lighting can set the mood for a home but equally its impact can be felt on the monthly power bill so it is vital to get the balance between atmosphere and energy saving right.
Fortunately most popular designs of light fitting are now available in energy saving versions, which can use up to 80 per cent less power than a standard light bulb and last six times longer.
Recessed downlights have proven a popular lighting choice for Kiwis in recent years but many of us remain unaware of the impact this lighting has on the thermal envelope of a home, punching holes in ceiling insulation where it cannot be abutted to or cover the lights.
For those that love the aesthetics of a recessed downlight, it is now possible to get IC-F rated lights, which insulation can either cover or abut to, meaning you don’t need to compromise the thermal performance of your home to create a lighting look you love.

You might be interested in reading: Tips on how to lower your energy bill.

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This article featured on page 84 of Issue 010 of New Zealand Renovate Magazine . New Zealand's first and only magazine solely dedicated to home renovations.


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*All information is believed to be true at time of publishing and is subject to change.

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