Today, Energy-efficient and environmentally friendly homes can be built with the proper techniques and methods in design and construction.
The minimum energy rating for most of Australia is six stars - set by the Nationwide House Energy Rating Scheme (NatHERS). This six-star minimum falls short of what is optimal in terms of environmental, economic and social outcomes. It’s also below the minimum set by many other countries. With current technology and knowledge, we should be building homes that meet higher standards than we currently do.
What is an energy rating
An energy rating indicates how much artificial heating and cooling is needed to keep the interior temperature within a comfortable range. The more stars a home has, the more energy-efficient it is and the less impact it will have on our environment. Homes with ten stars at the highest level of this rating do not require artificial heating or cooling all year round.
How energy ratings are measured
During the design phase of a building, an accredited NatHERS assessor will use several approved software programs to calculate the star rating of a new home. These tools use carefully calculate the amount of energy needed to heat and cool a home over a year and convert it to an energy rating. The assessment takes into account a large number of factors, with the more critical influencing elements including building location (climate zone); orientation; building materials; size, and type of glazing of windows; thickness of insulation (roof, walls, floors); ventilation; lighting; flooring coverings (carpet, flooring), etc.
Smarter design choices during the design stage can reduce the amount of energy needed to maintain a comfortable temperature with little to no additional building cost.
What does a higher rating mean?
The homeowner means that the house is naturally comfortable for a more extended period throughout the year. The ideal temperature for most people is about 21°C. An energy-inefficient home loses temperature and leaks cool air, leaving the house in constant need of heating and cooling. This unnecessary heating and cooling consumes about 40% of the home's energy and could be avoided.
Building a home with a higher energy rating means you can maintain ideal and comfortable temperatures all year round. A house that uses less energy to maintain a comfortable temperature reduces bill costs.
What does a new home builder need to do?
Before issuing a building permit, new home builders need to hire a qualified assessor to evaluate the design for energy ratings. If six stars are not initially achieved, the assessor will recommend changes to the design or house specifications.
Renovations or extensions that affect more than 50% of the volume of the existing house will also require the entire building to achieve six stars.
With the development of technology and experience, building an energy-efficient home is no longer difficult to achieve. However, it requires a builder to have an understanding and the desire to produce such an outcome. These houses require a little more thought and effort to construct.
We can improve energy efficiency in 6 ways.
1. Improve the use of sunlight
We know that the amount of sunlight a house receives is related to the angle the sun hits the earth and the time of day it shines. In Melbourne, the winter solstice is the day of the year with the least amount of sunlight (about 9 hours) and the sun's maximum altitude angle at midday is about 29°. The summer solstice is the longest day of the year (approximately 14.5 hours), and the maximum altitude angle of the sun at noon is about 75°. A building designer using computer-aided design software can calculate the effect of eaves, surrounding buildings and vegetation on the shading of a house at different times of the year, thus ensuring that the house has proper sunlight in the winter and proper shading in the summer. A good design makes the best use of windows to get more sunlight to heat the house in winter and less sunlight in summer.
2. Improve the orientation of the house
Since Melbourne is in the southern hemisphere, the sun rises in the east and sets in the west in a northerly direction. When choosing a house design, make sure that the most utilized areas are on the north side of the house. Take advantage of the winter sun to keep these rooms warm and bright. Minimize west-facing windows and ensure they are well shaded in the summer; try to avoid south-facing windows, which get little to no winter sun. Consider sharing walls with neighbours, particularly on the east or west boundaries.
Sharing walls reduces the wall area exposed to outside temperature fluctuations and, therefore, significantly reduces the heat loss/gain to the house.
3. Optimize window design
40% of the household's energy is lost through windows. This loss can be reduced by 80% with better design. The three main principles of energy-smart window design are listed below.
Maximise winter heat gain by orientating windows to the north and
sizing windows to suit the amount of thermal mass in the dwelling.
Minimise winter heat loss through appropriate window sizing,
together with double glazing and/or close-fitting internal coverings
such as drapes with pelmets.
Minimise summer heat gain by protecting windows with external
shading devices, sizing and positioning of windows.
4. Add insulation materials
Insulation creates an important barrier between the exterior and interior of your house. It keeps the heat out in the summer, while in the winter, it keeps the heat in. Insulating your home's ceilings, walls, and floors can save you up to 45%-55% of the running costs of your home. So add as much insulation as you can while making sure it is installed correctly and without gaps.
5. Take advantage of the thermal mass of building materials
Thermal mass is the ability of a material to absorb and store heat energy. Dense materials have a higher thermal mass. A material with thermal mass absorbs heat from the air in a room or from sunlight exposure. This heat is slowly released into the room for hours. Changing the building materials of a house from light (timber floors and timber walls) to heavy (concrete foundations and brick interior walls) can reduce heating and cooling expenses by 30% and 50%.
6. Seal the house
Uncontrolled air leakage can significantly reduce the energy efficiency of a house. Reducing uncontrolled air leakage can prevent heat loss in winter and prevent the entry of warm air in summer. This can save up to 20% on heating and cooling costs and improve comfort. Air can leak through door and window frames, exhaust fan openings, air conditioning vents, chimneys, joints in different building materials, dryer vents, and other places. By sealing these holes, the house's energy efficiency will greatly improve the energy efficiency of the house.
Concentric Integrity New Homes is committed to building energy-efficient homes that reduce home energy use, thereby increasing the comfort of your home and minimizing the bills you pay to maintain that comfort.
If you are building a new home, consider building energy efficiency early or contact me for a consultation.
我们知道，房屋接受太阳光的多少是与太阳照射地球的角度和光照时间有关。在墨尔本，冬至是一年中日照时间最少的一天 (约9小时)，太阳在正午时的最大高度角约为29°。夏至是一年中日照时间最长的一天（约14.5小时），太阳在正午时的最大高度角约为75°。建筑设计师通过计算机辅助设计软件进行遮阳研究，可以计算出屋檐、周围的建筑物和植被在一年中的不同时期对房屋遮阳的影响 ，从而确保房屋在冬季有适当的阳光，夏季有适当的阴影。好的设计可以使窗户得到最佳的利用，在冬季得到更多阳光加热，在夏季减少阳光照射。