# High-Rise Social Housing in Hot-Humid Climates: Towards an 'Airhouse' Standard for Comfort
## 1 Introduction  
The health and comfort of humans in urban areas are both compromised by high carbon emissions. In the Southeast Asia (SEA) region, these have increased rapidly. Malaysia is one of the five countries that have collectively contributed to 90% of the carbon emissions in the region, which is directly linked to an increase in temperature, projected to be in the country between 1.1 \({}^{\circ}\)C and 3.6 \({}^{\circ}\)C by 2095 [1]. The carbon emissions from the building sector have doubled from the 1970s, now representing 25% of the total country's emissions. The construction of residential buildings has quintupled during the last four decades [2]. In order to address this problem, the government has recently signed the Paris Agreement, committing to reduce 45% of carbon emissions by 2030, in accordance to the 2005 baseline. The ongoing People's Housing Programme (PPR) involves the construction of one million high-rise social housing units in Malaysia, but it does not addresses the comfort of the occupants and the wider environmental issues in full [3]. The local hot-humid climate, dense urban environment, layout andorientation of buildings, materials used for the building, and human behaviour contribute to a high indoor air temperature and humidity. Heavyweight construction with concrete panels or brickwork without insulation, which are, at the moment, the common systems of construction in Malaysia for these types of buildings, store heat and release it at night [4]. This gives no option to the occupants but to use individual air conditioning units to achieve thermal comfort, having the implications of high-energy consumption and carbon emissions, as well as unattractive urban facades (Figure 1). An additional problem is the outdated regulations. The current building regulations (UBBL) in Malaysia (a British colony until 1957), were implemented in 1984, based on the recommendations given by the United Kingdom's Building Research Station (BRS), currently known as the Building Research Establishment (BRE). The UBBL 1984 does not take Malaysia's hot-humid climate and the current issues concerning carbon emissions in full account [3]. Two main natural ventilation strategies are used for the design of these buildings: Temperature-induced stack ventilation using lightwells, air-wells, or atria, and wind-induced single sided ventilation for external rooms. The building regulations, which have not been revised for 35 years, only have requirements for the sizes of openings (Clause 39) and lightwells (Clause 40) [5]. The regulations establish that the minimum size of openings for natural ventilation purposes in residential buildings should not be less than 10% of the total clear area of the room. There have been recent developments concerning the use of green rating tools in Malaysia, which have encouraged a number of thermal comfort strategies, helping to improve the sustainable design of buildings [3]. However, they have not been able to acknowledge the current and future climatic conditions of Kuala Lumpur and address the required improvements in terms of occupant's health and comfort, as well as the reduction of carbon emissions. There are many challenges concerning the provision of conventional natural ventilation in dense urban areas such as Kuala Lumpur, including the problems associated with the urban heat island effect and air pollution (Figure 2). Considering the standard flat layout in these buildings (single-sided), and the high humidity and air pollution, cross-ventilation driven by ambient air movement is not an effective strategy for providing evaporative cooling. Effective ventilation is also hampered by insufficient wind movement: The average wind movement in Kuala Lumpur is 1.1 m/s at 10 m of elevation [6] and 4.4 m/s at 42.8 m of elevation [7]. There are no measurements at higher levels in the city, but we have data from Bangkok, another megacity in the SEA region, where the wind movement was 6.13 m/s at a 65 m elevation [8].