Is air conditioning still the best way to heat your home?

Your customers will always ask for the latest when it comes to passive heating and cooling. So what’s the answer?

• The way we heat and cool homes in Australia is changing.
• Using passive principles, a home can be comfortable year round.
• Star energy ratings have improved the regulations for passive heating and cooling today.

Who better to ask about the changing heating systems in homes today than someone who’s doing it day in, day out?

Liz Giorgio is the Founder and Principal Architect of Space&, a Victoria-based architecture and interiors consultancy, and she explains everything that’s happening to keep our buildings regulated from a temperature perspective.

Electrical Gems: How has the approach to heating and cooling buildings changed over recent years?

Liz Giorgio: Historically, buildings have been built with high thermal mass materials and limited expanses of glazing.

The result is a building that maintains a relatively consistent temperature without heat being lost through thin walls and glass.

“Think of an old solid brick home – they’re always more comfortable than their modern brick-veneer counterparts.”

The thick double-brick walls slow the transfer of unwanted external temperatures. In recent years, the importance of passive design principles and energy efficiency within the construction industry are becoming more widely acknowledged. These outcomes can be delivered in two ways:

• in the types of products and materials used
• in the layout and spatial planning of a building.

Although some energy-efficient building products can add significant cost to a building, adhering to passive design principles can drastically alter the energy efficiency of a home at no additional cost.

Modern building practice is rediscovering the importance of good passive design – allowing a building to utilise breezes and the sun to help regulate the internal temperature of the building.

Good design, coupled with innovative building products, is reducing our dependence on mechanical heating and cooling systems.

In 1993, the Nationwide House Energy Rating Scheme (NatHERS) was introduced. NatHERS assessors review house plans and specifications to determine what heating and cooling loads will be required to keep a new home within a comfortable temperature range.

Specialised NatHERS software will generate a star rating out of 10. The higher the star rating, the less energy is required to heat or cool the home.

The software assesses hundreds of data points, including the materials used, local climate, insulation, ventilation, solar access and orientation.

EG: What is common in building design today in this regard that wasn’t 10-20 years ago?

LG: Prior to 2003, energy efficiency requirements were not mandated by the National Construction Codes (formerly the Building Code of Australia or BCA).

If a home did not perform well thermally, mechanical heating and cooling systems were required, which are both costly to run and inefficient if the building envelope can not retain the generated heating/cooling.

Today, homes are required to meet a minimum 6-star energy efficiency rating. The star rating directly corresponds to the predicted loads required to keep a home within a comfortable temperature range.

Today, consumers can build or purchase homes that are designed specifically to reduce their energy consumption and running costs.

EG: Can excellent building design ever eliminate the need for additional heating and cooling?

LG: If a home is designed following passive design principles (using the sun for heat and light, shade and breezes for cooling), a home can be thermally comfortable year-round without the use of mechanical temperature regulation (excluding ceiling fans).

There are built examples of this across Australia, but perhaps my favourite is The 10 Star Home, built by the Sociable Weaver in collaboration with Clare Cousins Architects in Victoria.

This is Victoria’s first 10-star home that is both carbon positive and built to a ‘zero-waste’ building philosophy.

EG: What innovations are coming in this space?

LG: Australia is generally slow at adopting technologies of other countries. Building products and methodologies in Europe pave the way in intelligent design, however, these items are often costly in the Australian market.

There are a couple of interesting examples, however.

PCM – Phase Change Materials

These materials absorb and release latent heat when they change their physical state, ie from solid to liquid or vice versa.

The most well-known product in the industry is BioPCM, which comes in the form of a flexible plastic mat containing a matrix of sealed pockets containing an organic compound similar to wax.

When the ambient temperature heats up, the PCM material turns from a solid to a liquid state, thereby storing heat. As the ambient temperature drops, the PCM expels this retained heat and returns to a solid state.

Heat rises, making the ceiling the best location to install PCM, as it’s where where most of a building’s heating is usually lost.

SIPs – Structural Insulated Panels

SIPs consist of an insulated foam core sandwiched between two composite timber facings.

As the name suggests, the panels are structurally rigid, thereby allowing the walls, cladding and structure to become a single prefabricated unit. SIPs are air-tight, leading to better air quality within a building, and are about 50 per cent more energy efficient than traditional timber frame construction. SIPs are popular in Europe and gaining popularity in Australia.