This article first appeared in City & Country, The Edge Malaysia Weekly on October 10, 2022 - October 16, 2022

A hard one to catch, Green Real Estate Sdn Bhd (GreenRE) chief operating officer Ashwin Thurairajah squeezes in a quick phone call with City & Country while on a hectic business trip to London and shares some of his key insights on passive design.

“We have certainly been certifying [and looking] at more projects with passive designs lately with our tropical-centric metric system, and while it’s been encouraging, there is still a long way to go. There are more than one billion sq m in gross floor area in the property sector, with less than 10 million sq m being certified so far,” highlights the professional engineer. 

Championed by the Real Estate and Housing Developers’ Association Malaysia (Rehda) and formed in 2013, GreenRE acts as an assessment scheme and a green building rating system that is custom-made for the tropical climate.

Its activities include driving sustainability in the development and construction sectors through certifications and evaluating the performance of green buildings and townships; collaborating with other associations and non-governmental organisations (NGOs); and gaining feedback on policy proposals in a bid to put them forward to the relevant ministries.

According to Ashwin, the GreenRE rating levels are placed in four categories: Bronze, Silver, Gold or Platinum.

“A good example of a building with excellent passive design is the Pertubuhan Akitek Malaysia (PAM) Centre in Bangsar and Wisma Rehda in Petaling Jaya,” he says. 

“Wisma Rehda, for example, has two sides of its façade facing prevailing wind directions [in the north and south], with 14 out of 22 rooms enjoying natural ventilation of 63.6%. That is a good indicator that its passive designs are being utilised.” 

Passive design is defined as soft elements of a building that promote energy efficiency, water efficiency, environmental protection, indoor environment quality and carbon emissions calculation.

“Ideally, it should be considered in the first step of a construction of a building or home, because it would be quite difficult to correct later on. It has the greatest multiplier effect in terms of cost versus environmental benefit,” Ashwin says. 

Passive design is about optimising the layout, form and orientation of a building to reduce heat ingress and optimally harness ventilation and daylight. Ashwin adds that active elements comprising cooling, lighting, rainwater, solar photovoltaics and other technologies can be incorporated optimally.

Because of Malaysia’s tropical climate and needs, buildings and homes in the country can emulate the typology of a kampung house, which constitutes all the key elements of passive design, says Ashwin. 

“The design of a kampung house ticks all the boxes of good passive design — for example, its wood panels and windows promote natural ventilation and light. The construction elements found in a typical kampung house can be translated into modern buildings and homes.” 

Delving into the technical aspects and the complexities of passive design, Ashwin says: “The challenge is to extrapolate this approach and increase its adoption in a modern context.

“Passive design is about maintaining a delicate balance between the human need to improve lifestyles and feeling of well-being on the one hand, and preserving natural resources and ecosystems, in which we, and future generations would depend on [on the other].”

The first step is proper orientation of a building. “As the sun’s path in Malaysia is consistent throughout the year, minimising heat ingress through east and west façades is important.

“A useful rule of thumb or metric is our Overall Thermal Transfer Value (OTTV) formula for non-residential buildings and Residential Envelope Transfer Value (RETV) for residential buildings. The difference in formulae reflect the different functional and cooling approaches used in these different settings.

“Both approaches consider heat conduction through the façade and solar radiation through building glazing. Good heat-insulating materials and reduced glazing, especially on the east and west façades, will result in an optimal design,” he says.

Further, the prevailing wind direction in Malaysia is relatively consistent in a north-south orientation, thus designing openings on these sides of a building would be good to promote natural ventilation.

“In a work or dwelling space, keeping the maximum distance between these openings at 12m is a good rule of thumb for building designers,” says Ashwin.

He adds, however, that daylight capture is a double-edged sword and needs to be carefully considered. “Too much daylight will result in excessive glare and heating. We [at GreenRE] prescribe a daylight factor metric that optimises the competing demands of illumination, glare and heating. A good example of this metric being implemented is the Rehda HQ and low energy office (LEO) used by KASA (Ministry of Environment and Water).”

Other intricacies to consider include humidity. “Humidity poses a big challenge for building designers to incorporate more natural ventilation in functional spaces. Creative solutions include incorporating cost-effective dehumidifiers or adding vegetation,” says Ashwin.

Rain, and the tropical weather, can pose problems for incorporating natural ventilation as well. “However, this can be alleviated through careful wind-driven rain simulation and design of appropriate shading devices,” offers Ashwin.

“Electricity prices in Malaysia being fairly low results in greater use of ‘unnecessary’ air-conditioning. In many cases, a mechanical fan can offer comparable thermal comfort.”

The calibre of passive design in Malaysia is still comparable to other cities abroad that have their own green agenda. According to Ashwin, there are several innovative passive design strategies for reducing heat transfer into a building such as vegetated walls and green roofs that are “not common in Malaysia but widely used in Singapore”.

He says: “We encourage building designers to think outside the box and not stick to typical design. For example, space-cooling strategies such as air-purging and radiant-cooling through piped water can be more extensively applied.

“They need to focus on what goes on beyond the buildings and, at a city level, to reduce the urban heat island effect.”

Other solutions include providing sufficient green and blue spaces for residents and occupants.

“Parks, green spaces or water bodies with at least 800 sq m within 400m walking distance are good solutions. We also encourage building vegetation, vegetated walls and green roofs and the use of permeable paving materials with Solar Reflectance Index (SRI) of [more than] 29 [points]. Gravel and wood chippings also help to hardscape areas,” he says.

Open structures such as covered walkways, vine pergolas and open-air carparks can also be infused in passive design.

“There should be interconnectivity of biodiversity and green spaces for users and the public,” he says. 

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