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6 Actions For A Cost Effective Home Renovation

Renovating an old building that is full of character is not only a romantic dream for many of us, but also a more efficient use of our existing resources. Old buildings add charm and history to our landscape. We all remember timber features or the open fireplaces in an older home. Renovating is more environmentally friendly and helps us in NZ achieve the set goal of being carbon neutral by 2050. Why is it more sustainable to renovate than to build new? There are two reasons.

  1. The foundation, the roof and the structure are the three most carbon emission costly parts of your home. In a renovation they can often be left in place and re-used. This would mean a great amount of carbon emission can be saved compared to constructing a new building.

  2. Put carbon emissions aside, renovating would also reduce the amount of new materials required and cut down the quantity of construction waste created.

So how could we renovate our old house into a healthy, comfortable and efficient home?

At Circular Project, we spoke with an absolute expert in the field—Grant McSherry from Premium Homes in Christchurch. Grant specialises in helping people make their home renovation dreams come true. Together we have summarised 6 actions you should consider when planning your house renovation.

1. Think About Efficiency

Older buildings are often not insulated and cold. It means high costs to heat a house that often still feels cold. Living in an old house could also mean you need to wear many sweaters to stay warm. On average we spend 34% of our energy costs on space heating (1), about NZ$ 1,330 per year. The World Health Organisation recommends we keep our indoor temperature at minimum 18 degrees Celsius in winter. Most older properties only have this on very small spaces within the house. Efficient homes are healthier, cheaper to run and more comfortable to live in.

Installing insulation is an important way to keep the heat that is generated by your heating device or coming in from the sun in your house. Using natural insulation materials, such as sheep wool, is even better here. Besides the ability in keeping the warmth in your home, many natural insulation materials also give you better acoustics and help in regulating moisture in your home. Good insulation in your ceilings, floors and walls also mean a smaller heating source is sufficient to heat your home and lower your costs of heating.

Once we are able to contain the heat with insulation, we should also look in to how to create the heat. While some old houses may have multiple open fire places, others have none and are heated with small space heaters. The open fire places are neither efficient nor healthy. And most of the space heaters are not big enough for the rooms they are required to heat. We advocate for putting an efficient and renewable heating source, considering the ever-growing energy costs. With good insulation, a small efficient wood burner or heat pump might be already enough to keep you warm and cozy at home, for a fraction of the cost you paid so far.

Please find out with the energywise link below if you are eligible for a heating grant, covering part of the insulation and heat source costs.

2. Check Out Renewable Energy

With the ever-rising electricity prices and the progress in technology, many renewable technologies are well worth considering for your home. Take water heating as an example. Water heating accounts in the average NZ house for 29% (1) off their energy costs. The traditional method in most old houses is to heat water in a water cylinder with an electric element.

Taking a home in Christchurch as an example we took the energywise calculator to estimate alternatives for an electrically heated 180 litre tank (installed 2001 and insulated). We have estimated 3 daily showers and 1 weekly bath. Please be aware that if your cylinder is not insulated and older, your payback period would be even faster.

The payback periods are much faster than most people think, a more efficient system also adds value to your home in case you are thinking about selling it.

3. Pay Attention To The “Silent” Dangers: Humidity and Toxins

Most of the old buildings do not have ventilation systems, apart from opening windows. In our modern-day lifestyle we spend more time at home and create a great amount of humidity in the house. Putting on the kettle, cooking, having a shower or just breathing, all create humidity. In addition, using many more modern materials that do not help regulate moisture also creates the need for proper ventilation.

The result of too much humidity in our homes is mould and dampness. Those homes are expensive to heat and on top unhealthy to live in (5). The right amount of humidity lies at about 50%. Therefore, if you cannot ensure proper natural ventilation, look into a ventilation system. Conjointly we recommend the use of materials that help regulate moisture and avoid damp homes. This includes but not limited to natural insulation, plant life and breathable paint. Let’s get rid of damp homes.

A modern hidden danger is the toxins in the materials we invite into our homes. Furniture, paints and carpet can contain many toxins, which could enter into our bodies silently and potentially harm us and our families(6). Products are measured individually in their toxicity and deemed safe for use, however we in our home have many different toxic materials added together. Keeping toxic materials to a minimum will no doubt aid our health long term.

4. There Shall Be Light

Natural light from the sun heats up our homes and brightens our spaces. Older buildings however often are not properly orientated on site or laid out internally to capture sunlight. Your home might have been extended and with that lost direct sunlight. Or your house does not have enough windows to capture enough heat and light from the sun.

Many options should be explored: putting in more windows, updating old but stylish windows or replacing them with more efficient ones, installing light channels to light up darker spaces or changing the internal layout of your home. Every home has different circumstances and products have different payback periods and benefits.

5. Be Aware Of The Potential Cost

Let’s be honest, renovating can be costly. One of the reasons is the big unknown. For example, you might find some water damage or termites when you open up the walls to lay insulation. Another reason could be the time and resource you may need to put in to protect or restore a beautiful original feature. There could be nothing and no extra cost. But having a buffer in your budget would always be beneficial.

6. Set Your Priorities

It is important to set the priorities right, especially once the unidentified renovation need is identified. Knowing what is a necessity and what is a “cherry on top” would assist you in running your home improvement project smoothly. It would also help you keep focus and achieve what you set out to do.


Going forward renovating our old houses will become very important. Our homes can be efficient, sustainable and healthy. We need to do it. Not only because we owe it to ourselves, but also we owe it to our families and our planet.

To achieve that, together with Grant, we recommend:

  • Save on future running costs by insulating your home well and checking out renewable energy options.

  • Live dryer and healthier by ventilating properly, use natural / nontoxic materials and add sunlight to a dark home.

  • Speak with a specialist about a potential budget buffer for your particular project and focus your priorities.

Potential funding for your project can be found in several ways: for insulation there are grants on and the ANZ bank is providing for its’ customers a potentially interest free loan of $5k at present. Considering the smaller environmental impacts and large old housing stock in NZ, additional funding options will hopefully be explored in the near future to make renovating more attractive.

If you’d like to discuss about any points above, please do not hesitate to click the link below, or check out our building product information on our website.

Reference: ; ‘New Zealand’s Consumption’;; Infographic: What is the average New Zealand power bill?’; Author: New Zealand’s big winter switch; 25.05.2017;; ‘Average Electricity Costs per KWH; Author: Brendon O’Neill; 10.04.2018,; ‘Home heating costs in 2019’; 30.04.2019;; ‘ ‘Heavy burden’ of living in mouldy and damp homes, landlords still installing insulation’; Author: Mandy Te; 16.10.2019;; ‘Volatile Organic Compounds’ Impact on Indoor Air Quality’; United States Environmental Protection Agency; checked 29.01.2020;

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