New Zealand is fast approaching its hottest months of the year with summer just around the corner. During this time, where there are more temperature fluctuations and greater extremes, we truly begin to notice the thermal efficiency (or unfortunately inefficiency) of our homes.

Whether it’s the biting cold of winter or the humid discomfort of summer, the way in which a home is built can greatly impact our living comfort. While there are methods to cool our homes during the hot summer months, most require electricity. This increased energy demand not only raises electricity bills, but also contributes to a larger carbon footprint.

To achieve a more thermally efficient home it is essential to focus on the building’s structure and materials, placing emphasis on thermal mass principle and passive heating/cooling strategies.

Thermal Mass

Thermal mass is a fundamental concept in building design. It refers to a material’s capacity to absorb, store, and release heat. Different materials have varying degrees of heat capacity, leading to efficient and inefficient construction solutions. When the sun shines throughout the day, the building absorbs and stores heat, which is then released inside the building.

Materials with higher thermal mass able to resist temperature fluctuations outside (high thermal inertia), are crucial for maintaining stable indoor temperatures throughout the year.

Passive annual heat storage (PAHS) is an energy-saving building concept that revolves around passive heating and cooling of homes. PAHS relies on insulation, thermal inertia, and the heat capacity of materials to regulate indoor temperatures as opposed to electricity all year round.

Passive heating and cooling not only lower costs but also contribute to a more environmentally friendly and sustainable approach to temperature control.

Concrete Solutions

As we strive to make future homes better suited to New Zealand’s diverse weather and temperatures, it is imperative we focus on building materials that can help achieve this. Timber framing is NZ’s traditional method of construction, yet has a low thermal mass, meaning it cannot absorb, store and release much heat, resulting in inefficient thermal performance.

A common solution that exhibits a high heat capacity is concrete. It is able to store heat effectively and slowly release this energy for stable temperatures.

However, we can take it a step further by introducing insulative qualities to the concrete by using insulated concrete formwork (ICF), which offers exceptional thermal performance. ICF is made from two layers of insulating EPS filled with concrete. After the concrete cures the EPS forms are kept in place, which significantly improves thermal performance.

ICF covers all areas of thermal efficiency we aim to achieve: stable temperatures all year round, cost savings, less energy reliance and consumption, which all ties into the larger picture of significantly improved comfort.

This construction solution helps to keep homes tolerable during summer due to its thermal mass slowing down the release of heat throughout the home. It also ensures homes stay warm on cold days by retaining heat. This thermal efficiency and insulation helps prevent issues like damp and mould, improving the overall wellbeing of occupants.

Future Design

Thermal efficiency in building design is a fundamental consideration for homes in NZ to raise living conditions. Constructing buildings from materials with high thermal mass, coupled with passive heating and cooling strategies, can significantly improve living comfort and sustainability.

Innovative solutions like ICF construction can transform the way we build our homes, offering stable temperatures, cost savings, and premium comfort. Whether you are looking to build your home or build a development, thermal efficient solutions should be considered early in the design process for a higher standard final build.

Anthony Corin and his team specialise in property development and construction using ICFs and operating through a relational contract, open-book system. Shorcom Ltd, 0800 SHORCOM, www.shorcom.co.nz