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  • Alun Carter

What is Home Performance and why as Kiwis we should be putting more effort into this. (Part 1)

Ever since humans have sought shelter from the weather, predators, vermin, and other humans there has been an effort to find ways to improve this shelter. Initially natural shelters were sought, then these were modified until completely man-made standalone buildings were constructed. Over time as better building materials, systems and technology became available these dwellings have been steadily improved.

In recent years the focus of this development has become more on house performance in terms of energy use and comfort, and this interest is growing exponentially. As has been well documented in various sources New Zealand is lagging other similar developed nations with regards our housing energy performance standards.

In order to correct this and make our houses more of a home we need to understand:

1) Why we need to improve our houses energy performance?

2) What is causing our poor house performance?

3) How we can improve our house performance?

Why improve house performance

There are arguably four reasons why we should improve New Zealand house performance.

Personal Comfort

We all have a comfort tolerance when it comes to our living environment where we feel uncomfortable if it is too hot, cold, humid, draughty/windy and with regards air quality. This tolerance varies between individuals depending on their metabolism, activeness, working environment, previous experience, age and personal health. It will also vary depending on behavior such as willingness to putting on extra clothing when too cold. For this reason, BRANZ HEEP Study 2006 recommends evening living room temperatures should be between 19.5 and 25 degrees C for comfort.

Traditionally in New Zealand there has been a tolerance to poor living conditions with the attitude to “toughen up”. However, as time passes, and more and more Kiwis experience better housing standards overseas they are becoming less tolerant.

So, as it has been shown possible to have homes which are comfortable to live in then why should we accept living in houses which are not? For example, why should we get out of a shower or bath in the middle of winter and be cold when there is no need to.


New Zealand has approximately 1600 excess winter deaths per year (University of Otago Wellington Studies). International statistics shows we have the fourth highest hospital admission rates for Asthma in the OECD with 15% of children (aged 2-14) and 11% of adults on Asthma medication. We also have Rheumatic fever which has largely been eradicated in most other OECD countries. Although far more prevalent in other regions of New Zealand Marlborough, fortunately, has a relatively low Rheumatic fever rate of 0.8 per 100000.

According to Building Research Assoc. of New Zealand (BRANZ) Household Energy End-use Project (HEEP) the average evening living room temperature in New Zealand (NZ) is only 17.9°C and bedrooms 13.6°C overnight. As this is an average for many houses there would be large amount of times below these temperatures. When one considers that physiologically at 16°C it is harder to breath and at 12°C heart function is affected this can go some way to explain our 1600 annual excess winter deaths.

The BRANZ House Condition Survey 2015 (HCS-2015) found 56% and 44% of rental and owner-occupied properties respectively had visible mould (Nb. More than half of recordings was at the level of specs). Mould is an indicator of dampness and cold.

These temperature ranges and humidity ranges can often fall outside of the World Health Organisation (WHO) guidelines. WHO guidelines are that the ideal home environment should be between 18°C and 24°C and have a relative humidity of between 40 and 60%. This range is even more narrow if the occupant is very young, elderly or suffering from a physical health condition.

How New Zealand House conditions compare to WHO healthy Temp and Humidity recommendations (Guy Penny, NIWA)

Housing with conditions outside the WHO guidelines are more prone to mould growth and development of certain pests and pathogens. There are now numerous studies which have found a strong correlation between housing conditions and occupant general health.

Naturally no one likes or wants to be sick and feel unwell so if we can avoid this by improving our housing stock, it really is a no brainer decision.


Various studies show that on average a house spends 30% of their energy on Home Heating and cooling, one third on Heating Water and the remaining third on lighting and appliances. With the increase in technology available appliances are becoming a greater proportion of a household’s energy bill. Dampness of insulation can reduce its effectiveness resulting in greater heat loss. This is in addition to the increased energy required to heat a damp home. Thus, with our ever-increasing cost of energy in relation to income, inefficient energy use in houses can put a large financial burden on some families. This can result in a phenomenon called Energy Poverty where some families actively decide or are just not capable of heating their homes effectively. This only exacerbates the health impacts on these families.

The increased cost of seeking medical care can be a significant cost to occupants making their financial situation more difficult. Ill health affects occupant work performance with higher rates of sick leave taken. This could limit potential personal development, limiting promotion opportunities and therefor increased earnings.

A typical New Zealand house has a large variation in temperature and humidity on a daily and annual basis. This can result in cold internal surfaces which increases the chance of water condensing out from the surrounding air. This condensation can cause water damage to materials. Damp houses deteriorate more quickly requiring more maintenance and repairs. Housing repairs can be expensive and take a lot out of a family’s budget.

For the above reasons poor housing can limit wealth growth of the family unit affecting both short and long-term quality of life.

At a National level high bills and ill health can add stress and affect occupant mental health which can arguably contribute to substance abuse, crime and family violence. Energy Poverty increases dependence on state welfare system. This all adds costs to the National health, criminal and welfare system.

Increased Energy demand through population growth and increase in appliances would require new and/or alternative energy generators to be developed and built along with upgrades to the current distribution network resulting in increased energy costs to the user and State-Owned Enterprises.

It is important to note that savings in energy use can be cumulative in that starting with one small saving can release funds for further home improvements generating even greater savings.

With better household energy conservation and efficiency of use decisions could be made to use the financial savings on other priorities such as education, health, investment, retirement or more pleasurable activities such as holidays etc.

Logically then if by simply improving the quality of our housing, we could improve our own personal and National financial situation then we should do this.


New Zealand is world renowned for its natural beauty and relatively untouched landscape. We pride ourselves on our clean green image on which many of our businesses rely for their success (e.g. Fonterra & tourism).

Residential buildings (apartments & houses) in 2015 consumed 33% of the country’s electricity and 12% of the total energy (including wood, coal, petrol etc) used in New Zealand.

New Zealand population size is increasing, the number of occupants per household is decreasing, there is increased demand for larger housing (Stats NZ). This along with the availability of electronic technology and its associated appliances is creating more demand and consumption of energy in residential homes.

All energy production whether it be green (wood, wind, solar, geothermal, Hydro) or fossil (gas, coal, Oil) require resources to generate. On top of the energy resource itself these resources include construction materials to build generation plants and transmission networks, fuels to operate these, manpower to build, operate and maintain, finances to develop and operate, in addition to the land occupied to undertake these activities.

Unless we start to use our energy more efficiently and conserve where we can, more energy generators will be needed to meet demand. The result more of our currently unused natural environment will be lost to provide resources. Some of these resources are finite and will run out with time. In addition, when some resources are produced and then consumed, they release waste by products some of which are toxic to humans and the environment. If we can reduce the amount of resources we consume now, the longer they will be available to be enjoyed by us and future generations.

Whilst it is acknowledged that to carry out the improvement to the current housing stock will require additional resources it is generally thought that with time, this would be significantly less than those required to maintain the status quo.

Based on the thought process that by improving our housing we will be able to preserve our incredible Natural Resources for future enjoyment then we should begin the process now.

Thus, improving the quality of our houses so that they perform better, last longer and use less energy over their life span could improve Kiwi quality of life, finances and enable us to do more. These are very good arguments as to why we need to improve house performance in New Zealand.

Watch out for Part 2 in this series.

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