38Mews is a net-zero energy house located in Kota Damansara, Petaling Jaya. Photo: Lin Ho

Architect Chan Mun Inn’s residence is a net-zero energy house. That means he does not pay any electricity bills.

Located in Kota Damansara, Petaling Jaya, 38Mews is where he and his wife – and their 10 cats – live.

A net-zero home is one that makes as much electricity on-site as it consumes over the period of one year.

30Mews is designed as a low-energy house and Chan has achieved that by incorporating specific design features.

For one, the house is completely elevated to promote air flow while its windows are designed and positioned to facilitate cross ventilation and natural lighting. Roof and walls are also well insulated while overhangs provide shading.

Chan lives in a net-zero home, which is one that makes as much electricity on-site as it consumes over the period of one year. Photos: The Star/Art Chen

Rainwater is collected from its entire sloping roof into a tank on the ground floor to water plants and trees. Solar panels contra off the electricity that is used, half of which goes towards charging his hybrid car.

The house is a good example in sustainable design, which can be defined as building and living in a way that ensures the long-term health of both humanity and our environment.

With greater awareness of sustainable living these days, many people seek out home designs that do minimal harm to the environment and use low energy.

“Sustainability in design can be broken into active and passive design. The passive part is about finding ways to not use energy, so we need good insulation and to fully understand how tropical weather works and how the house sits within the tropical landscape, ” said architect Lee Cherng Yih, founder of FormZero.

Lee says sustainability in design can be broken into active and passive design, but owners need to embrace a sustainable lifestyle too.

“The active part is how to save and use less energy. But the third part, which is hard to quantify, is the practices of the owners living in the house.

“If they turn on the air-conditioning at full blast all the time, then that is not sustainable.

“We always discuss with the owner first about their living habits, and how much comfort and ‘discomfort’ they can accept, when designing a house. There is some inconvenience to sustainable living that we must embrace, ” he said.

Lee gave an example of one of his projects called the Window House in Kuala Lumpur.

“Internally, there are no windows in the house. At first, I was not sure if the client could accept that, since mosquitoes and birds could fly in.

Window House features a concrete shell that wraps the house from east to west. Photo: The Star/Azman Ghani

“But today, they have come to accept it. They like the good ventilation and yes, the birds and mosquitoes do come in, but they have learned to live with the design, ” added Lee.

Chan, a director at Design Collective Architects, said almost all the projects under his firm feature solar panelling and net energy metering with SEDA (Sustainable Energy Development Authority).

Net energy metering is a system in which a utility company pays you for the excess electricity generated by your solar panels.

However, Chan added that solar panels are still not cost-effective for now.

“It depends how much the owner wants to invest in the net metering system because return-on- investment still takes a long time, around eight to 10 years, ” he said.

Chan highlights one key factor in sustainable design – walls and roof insulation.

38Mews is completely elevated to promote airflow while its windows are designed and positioned to facilitate cross ventilation and natural lighting. Photo: Lin Ho

“External walls need to be double-brick cavity walls so that when the sun hits, the outer layer is hot but the inner layer remains cool. That reduces the amount of heat that reaches the interior.

“There are additional costs involved with this kind of wall but it provides good insulation. Even without air conditioning, the interiors are cool. And even if you use air-cond, it takes less energy to cool down the interiors because it is already cooler, ” explained Chan.

The other part is the roof structure, he added.

“Old terrace houses have almost zero roof insulation. Therefore the heat comes straight in.”

Lee said the biggest challenge is fighting against the comfort of air conditioning.

“People always think that if their house is well-ventilated, they will get a cool house. No. You can’t compare the coolness that air conditioning offers you.”

Chan added, “I think the idea of good ventilation is this: you can cool the interior down to close to the outside temperature.

“The courtyard is a good design feature but unfortunately many Malaysians tend to cover it up. The old terrace houses used to have courtyards but people put a roof over it. But courtyards cool down a house very well, allowing hot air to go up and out.”

As architects, both Chan and Lee hope that more people will truly embrace the principles of sustainable living.

“Sustainable living requires a change of lifestyle. I hope more people will understand that and not just want a sustainable design for the sake of it.”