Building a new house is always exciting. As you know your requirements and have few performance expectations from your new home creates an opportunity to go for a customised floor plan. If you want to be heavily involved in each step of building process, already looking for land with decent neighbourhood and proximity to school, park and shops than customise home option is just for you.

It is important for homes be designed or modified to ensure that the occupants remain thermally comfortable with minimal auxiliary heating or cooling in the climate where they are built. Passive design — working with the climate, not against it — is an important component, as are energy efficient heating and cooling systems, and smart behavior by the occupants.

The Bigger Goal

The 40% of household energy used for heating and cooling to achieve thermal comfort could be cut to almost zero in new housing through sound climate responsive design. . Taking into account current consumer preferences and industry practices, halving the rate to 20% is a highly achievable in the short term.

Reducing energy bills in existing homes

Reducing or eliminating heating and cooling needs in existing homes is a significant challenge, particularly those designed and built before building energy efficiency standards were introduced, when appliances were effective but inefficient. Based on 1.5% annual renewal rates, at least 50% of our current housing stock will still be in service in 30 years’ time.

New homes built now will be in service in future times when we expect to see significant changes in the climate. Designing for today’s climate is important; ensuring that those designs can be just as efficient after 30 years of climate change would certainly be desirable.

reduce energy cost

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Costs Involved

Affordability is often cited as the main barrier to greater efficiency but increasing energy costs are rapidly shifting the affordability focus from initial or upfront cost to ongoing or operational cost. With this shift, high levels of thermal performance are becoming increasingly valuable and the payback or amortisation period for thermal performance upgrades is diminishing rapidly.

This introductory overview of key design objectives and responses to creating thermally comfortable homes in each main climate zone in Australia needs to be further refined and customised to your individual site, locality and design brief. Use this overview, and the references to other articles, to access more detailed information as you proceed through the various stages of designing, purchasing or altering your home.

Human Thermal Comfort

Humans are comfortable only within a very narrow range of conditions. Our body temperature is about 37°C, despite the fact that the body generates heat even while at rest: we must lose heat at the same rate it is produced and gain heat at the same rate it is lost. The diagram below shows the various ways by which our bodies achieve this.

Human thermal comfort has two components: psychological and physiological. Both are governed by the processes in the diagram but reach the brain and trigger responses by very different pathways. Both needs must be met before we feel truly comfortable.

The main factors influencing both physical and psychological human comfort are:

Temperature
Humidity
Air movement (breeze or draught)
Exposure to radiant heat sources
Exposure to cool surfaces to radiate, or conduct to, for cooling.

Human Thermal Comfort

Weathers Around Melbourne

WEATHERS AROUND MELBOURNE

It’s a common saying that we got all four seasons in one day around Melbourne, so it beco
mes very important to have such a smart design that can cope with all kinds of temperature variations.

Four distinct seasons: summer and winter exceed human comfort range; spring and autumn are ideal for human comfort Mild to cool winters with low humidity

Hot to very hot summers, moderate humidity.

KEY DESIGN OBJECTIVES

These climates present cost effective opportunities to achieve carbon zero or positive outcomes because they require relatively simple design adjustments to achieve low or zero heating and cooling energy use (NatHERS ratings of 8−10 star). Minimising heating and cooling energy use should be a primary design objective.

Design For Climate

It is important to consider the climate zone where a building will exist. In Australia there are 7 core climate zones. The properties of a building in each of these zones would need to vary in order to accommodate the specific climatic requirements of that zone.

Where windows are concerned it is important to select a window suitable for the climate zone it will be used in. For example in a cool climate a window with high solar heat gain to maximise the use of free heating energy would be appropriate. In a warm climate you may wish to select a window which offers low solar heat gain properties to avoid unwanted heat entering the home through solar radiations.

Orientation

A home that is well positioned on its site delivers significant lifestyle and environmental benefits. Correct orientation assists passive heating and cooling, resulting in improved comfort and decreased energy bills.

In hot humid climates and hot dry climates with no winter heating requirements, orientation should aim to exclude sun year round and maximise exposure to cooling breezes.

In all other climates a combination of passive solar heating and passive cooling is required. The optimum degree of solar access and the need to capture cooling breezes will vary with climate.

Where ideal orientation is not possible, as is often the case in higher density urban areas, an energy efficient home can still be achieved with careful attention to design.

Orientation for passive heating is about using the sun as a source of free home heating. Put simply, it involves letting winter sun in and keeping unwanted summer sun out.

orientation

shading

Shading

Shading of windows and doors is a critical consideration in passive design. Unprotected low performance glass is the single greatest source of heat gain in a well-insulated home. Shading requirements vary according to climate and house orientation.

In climates where winter heating is required, shading devices should exclude summer sun but allow full winter sun to penetrate.

This is most simply achieved on north facing walls. East and west facing windows require different shading solutions to north facing windows.

In climates where no heating is required, shading of the whole home and outdoor spaces will improve comfort and save energy.

Passive Solar Heating

Passive solar heating is about keeping the summer sun out and letting the winter sun in. It is the least expensive way to heat your home.

Solar radiation is trapped inside the home using correctly oriented (north facing) windows exposed to full sun. Window frames and glass have a significant effect on the efficiency of this process. Trapped heat is absorbed and stored by materials with high thermal mass (usually masonry) inside the house. It is re-released at night when it is needed to offset heat losses to lower outdoor temperatures.

Design floor plans to ensure that the most important rooms (usually day-use living areas) face north for the best solar access.

Heat loss is minimised using insulation – select aluminium windows and aluminium doors with low Uw Values which offer good insulation properties. ,

Air infiltration is minimised with airlocks, draught sealing, airtight construction detailing and quality aluminium windows and aluminium doors.

Passive solar houses can look like any other home but they are more comfortable to live in and cost less to run.

solar-passive-heating

passive cooling

Passive Cooling

Passive cooling is the least expensive means of cooling your home. It is appropriate for all Australian climates.

Passive cooling maximises the efficiency of the building envelope. it minimises heat gain from the external environment.It facilitates heat loss to the following natural sources of cooling:

Air movement – Cooling breezes – Evaporation – Earth coupling.
Air movement is the most important element of passive cooling. It increases cooling by increasing evaporation rates. Generally, cross ventilation is most effective for air exchange (building cooling) and fans for air movement (people cooling). Windows are a great source of cross flow ventilation.

Correct positioning of windows and doors is essential to facilitate air movements. Use windows designed to deflect breezes from varying angles. Locate windows on walls with best exposure to common cooling breezes and design for effective cross flow of air.