KUALA LUMPUR: Having lived in a medium-cost apartment for over 11 years, architectural designer Huda Mahmud understands the challenges B40 families staying in compact high-rise spaces face during hot weather.

"I like the sunshine but I don't like the indoor heat. Whenever I stay indoors, I carry my hand fan everywhere to keep myself cool.

"As much as I want to advocate passive cooling in small houses, which is very ideal and achievable, I acknowledge that the current house designs don't really cater to efficient natural ventilation. This is why most low-cost housing residents resort to mechanical ventilation by installing air conditioners and roof turbines for immediate respite from the heat," Huda, 45, who resides in Rawang, Selangor, told Bernama recently.

The ongoing heatwave in Malaysia will likely be around for a few more months, according to media reports.

On May 2, Natural Resources and Environmental Sustainability Minister Nik Nazmi Nik Ahmad said the El Nino phenomenon currently hitting the country is expected to continue for the next two months. He also said forecasts indicate that this year could be the country's hottest year.

According to the Malaysian Meteorological Department (MetMalaysia), Malaysians can expect drier conditions over the next few months.

On May 25, MetMalaysia issued a Level 1 heatwave alert to three districts in Peninsular Malaysia and two districts in Sabah after they recorded maximum temperatures of between 35°C to 37°C for three consecutive days.

On May 26, 13 districts in Peninsular Malaysia and two districts in Sabah recorded Level 1 temperatures, while 21 districts in Peninsular Malaysia and one district in Sabah recorded Level 1 temperatures on May 27.

REDUCE INDOOR HEAT

People residing in high-rise, low-cost flats and apartments, comprising units with total floor areas of below 900 sq ft, are feeling the effects of the heatwave more than others.

This is because their buildings, usually designed with cost-effectiveness in mind, tend to be more compact and congested and lack good air circulation and ventilation systems.

In Huda's case, she tries to keep her apartment unit cool by ensuring all the windows are open early in the morning to let in the cool air. She closes them in the afternoon to prevent the hot air from entering.

"I also keep the windows open at night to allow cool air to enter. It helps to bring down the (indoor) temperature a bit. I also use semi-blackout, dark sheer curtains or blinds to filter the glare (sunlight) while still allowing natural light in," she said.

Sharing a few tips on what flat or apartment residents can do to make their units cooler, Huda said painting the walls in lighter colours can reduce heat absorption. And, if the housing managements allow it, occupants can have awnings fixed above their windows as these fittings reduce solar heat gains.

For Huda, good ventilation means allowing cool air in and pushing out the hot air that accumulates in the house.

"To achieve this, a simple method is to have openings on the bottom and top parts of external walls, like doors and windows. It also depends on the placement of these openings within the units to facilitate cross ventilation.

"In buildings with two to four (residential) units on each floor, the floors are designed so that cross ventilation happens from the front to the back of the units," she explained.

However, added Huda, housing design styles have changed over the years, transitioning from walk-up flats to high-rise structures with lifts. Previously, there would be two to four units per staircase entrance but now that has changed to 16 to 22 units per floor.

"This is due to floor efficiency that developers or building authorities want to achieve… they want to put in as many units as they can on each floor," she said.

She said in most high-rise flat or apartment buildings, the residential units are configured along a main corridor which means the front door of each unit faces the front door of the opposite unit. However, due to privacy and safety reason, the occupants prefer keeping their doors closed, which leads to minimal cross ventilation happening in the units.

COST IMPLICATIONS, LACK OF INCENTIVES

Most experts Bernama spoke to agreed that natural ventilation has to be a key component of buildings today, especially affordably priced flats and apartments, in order to provide the building occupants fresh air and a cost-effective way of saving energy.

Natural ventilation essentially means using passive strategies to supply outdoor air to a building's interior for ventilation and cooling without using mechanical systems.

However, most high-rise affordable housing schemes in Malaysia – that look like pigeon holes from afar – are designed in a way that does not permit natural ventilation.

According to REHDA Institute's report 'Affordable Housing II – Closing the Gap: A Strategic Approach to Balancing Supply & Demand' launched on May 14, although there is a growing request for buildings accredited as environmentally friendly, obtaining a green building certification – which includes natural ventilation as part of a building's elements – for affordable housing projects is not a primary concern for developers in Malaysia.

(REHDA is the training, education and research arm of REHDA [Real Estate and Housing Developers Association] Malaysia.)

REHDA Institute Research and Education director Malathi Thevendran said this is due to the significant costs associated with its implementation.

"Developers have embraced several ESG (Environmental, Social and Governance) aspects within selected affordable housing developments, with the popular environment-related ESG initiatives being energy efficiency, environmental protection and indoor environmental quality," she said.

However, she added, there are some limitations to the implementation of ESG in affordable housing schemes.

Pointing to some of their findings published in their May 14 report, Malathi said 82 percent of developers think the limitations are due to cost implications while 45 percent cited lack of government incentives; 21 percent, limited availability of sustainable material; 15 percent, limited public awareness; and 15 percent, lack of expertise.

NATURAL VENTILATION

Universiti Kebangsaan Malaysia Department of Earth Sciences and Environment senior lecturer Associate Prof Dr Mohd Shahrul Mohd Nadzir, meanwhile, said future affordable housing projects should consider building orientation to maximise natural ventilation and minimise heat gain.

"Designing buildings with adequate shading, balconies and ventilation pathways can significantly improve indoor comfort.

"And, implementing green roofs (rooftop gardens) and living walls (walls covered with plants that are growing in containers or on special material attached to the wall) will help insulate buildings and reduce heat absorption. These systems provide natural cooling and improve air quality. Indoor air quality and thermal comfort are important to monitor too," he said when contacted by Bernama.

He said proper insulation to walls and roofs, a cost-effective way to improve energy efficiency and comfort, can also help keep indoor temperatures stable by preventing excessive heat gain during the day and heat loss at night.

"Using cool roofing materials that reflect more sunlight and absorb less heat can help lower the roof temperature and reduce the heat transferred into the building. Light-coloured and reflective roofing materials are particularly effective," he said.

Other design elements that can be integrated into new housing developments are passive solar design principles such as the strategic placement of windows and shading devices that can help regulate indoor temperatures naturally, he added.

Mohd Shahrul, who is also an air quality expert, also proposed that high-rise housing developers plant trees, shrubs and other vegetation around buildings to provide shade and mitigate the urban heat island effect.

He said buildings located in densely populated urban areas are often subject to the urban heat island effect, where temperatures are higher due to the concentration of buildings, asphalt and reduced vegetation.

"High-density apartment complexes may have limited natural ventilation and airflow, leading to increased indoor temperatures. Ensuring adequate spacing between buildings and incorporating design elements that promote cross-ventilation can alleviate this issue," he added.

LONG-TERM MITIGATION

Andrew Tirta, principal and director of VERITAS Indonesia, which provides cost-effective design solutions to real estate developers, said developers can implement long-term mitigations by selecting locally sourced and sustainable building materials with good thermal insulation properties to improve energy efficiency and comfort.

"They can use materials with low embodied energy and high durability to reduce environmental impact and maintenance costs," he told Bernama in an email interview.

Andrew, who is a certified architect in Indonesia, also said the concentrated use of air conditioning in high-density housing areas can contribute to the formation of urban heat islands, where densely built-up areas retain more heat than the surrounding areas, leading to higher temperatures and health risks.

"However, if it is really necessary (to have air conditioning), it's wise to install energy-efficient HVAC (heating, ventilation and air conditioning) systems to minimise energy consumption and operating costs," he said.

UKM's Mohd Shahrul said the widespread use of air-conditioners (AC) can contribute to greenhouse gas emissions and exacerbate climate change as they release heat into the surrounding environment.

"Many AC units use refrigerants that are potent greenhouse gases such as carbon tetrachloride, hydrochlorofluorocarbons and chlorofluorocarbons which can cause ozone depletion.

"Although newer AC models use more environmentally friendly refrigerants, improper disposal and leakages can still pose environmental risks," he said.

Mohd Shahrul also suggested that governments and local authorities provide incentives to retrofit existing buildings with energy-efficient cooling solutions and implement passive cooling measures.

He said the management bodies or residents associations of buildings must encourage their communities to engage in collective efforts to improve their living environment by planting trees.

"There must be more awareness about the practical measures homeowners can take to mitigate indoor overheating. Educational campaigns can also provide valuable information to homeowners on do-it-yourself solutions," he said.