"Achieving high thermal performance without compromising any of the other equally important features of a design is not as easy as it sounds. An architect has to weigh up many competing ideas when designing an energy efficient house."
- Ben Bell, HERS Assessor
We recently asked HERS (Home Energy Rating Scheme) specialist Ben Bell to evaluate two of our standard designs. The results have put ebode into a very elite niche of extremely efficiently designed sustainable homes.
ebode's Light House design achieved a rating of 8, while the Freedom 2 scored 8.5 out of a possible 10. By contrast, the average new house in New Zealand scores 4-5 at most, and older homes usually only achieve a rating of 2 or 3.
Ben says it's "pretty difficult" for a home to score above 7 without very specific eco design, and 8.5 is the highest rating he is aware of given to a residential home in New Zealand. "To achieve any more than this would require too many compromises in terms of lifestyle and aesthetics for the majority of people," says Ben. When asked about the reasons why he thinks good thermal design is critical in the design of any
home, Ben says:
"As anyone from the northern hemisphere will tell you, many of the houses New Zealanders live in are cold, damp, and difficult to heat in winter, but too hot in summer. One of the main reasons for this is their poor thermal design. In the past, architects did not pay enough attention to the thermal performance of the houses they were designing, party because energy was cheap, but also because their clients did not demand it."
"Times have changed. It is now recognized that a well designed house should maximize the benefit of winter sun, be easy to heat, and retain that heat during cold winter nights. It should also provide a cool and comfortable environment to live in during the summer months. Doing this using good passive thermal design not only provides a healthier home, but it makes your home far less expensive to run on an ongoing basis."
"Achieving high thermal performance without compromising any of the other equally important features of a design is not as easy as it sounds," continues Ben. "An architect has to weigh up many competing ideas when designing a house. Using a computer model such as a HERS rating to calculate the energy performance of a house design at the concept stage is a very valuable tool. It allows the architect to evaluate the energy performance of the design at an early stage, and to consider the impact of various features before the design is fixed."
Ben was very impressed that the ebode homes he assessed rated so highly without any modifications required to the design. In the next few months we will continue with the assessment programme for all standard ebode designs, and will offer free HERS assessments on all custom designed homes in future with the aim of ensuring all ebode homes score similarly well.
Ben says that a HERS rating is also a valuable tool for home owners, assisting them to make the most cost effective and practical decisions when selecting a home or working with an architect to design and specify materials for their home. "We all want to live in warm, comfortable houses that are easy to heat and cool," says Ben. "You can use HERS ratings to compare homes you may be considering with each other; or help you to evaluate various aspects of your home's design and materials at the planning stage to achieve the best possible performance."