Air-conditioning cools a room after heat has already entered the housing system.
HDB’s town-cooling strategy starts earlier.
Can the building absorb less solar heat?
Can the playground sit in shade?
Can block orientation improve natural ventilation?
Can greenery be placed where surfaces receive the most heat?
These questions move thermal comfort from the private air-conditioner into public planning.
Official HDB references: Green Towns Programme, Green Innovations and HDB to Extend Cool Coatings Initiative to All Existing HDB Estates.
For the whole public-housing system, return to How HDB Works in Singapore. For the broader physics of urban heat, see How Heat Moves Through Hougang.
This article reflects official HDB information available on 4 September 2026.
The short answer
HDB reduces heat stress using several layers at once:
- cool coatings reflect more solar heat from building surfaces;
- block orientation can improve natural wind flow;
- shade planning keeps outdoor amenities out of the harshest sun where possible;
- greenery is placed to cool exposed areas and reduce heat gain;
- landscape and town form influence how heat accumulates and how air moves.
HDB says cool coatings on building facades can help reduce ambient temperature by up to 2°C. Following the Tampines pilot, HDB is working with Town Councils to extend cool coatings across existing HDB residential developments islandwide by 2030.
REFLECT HEAT + CREATE SHADE + MOVE AIR + ADD GREENERY = LOWER THERMAL STRESS BEFORE THE AIR-CONDITIONER STARTS.
Heat stress begins at the surface
Sunlight reaches a roof, wall, pavement or road.
Part is reflected.
Part is absorbed.
The absorbed energy warms the material.
The warm material then transfers heat to the surrounding air and nearby spaces.
Dark or heat-absorbing surfaces can therefore become thermal reservoirs during the day.
Town cooling begins by changing what happens when sunlight first touches the built environment.
Cool coatings change the surface energy balance
Cool coatings are formulated to reflect more solar radiation than ordinary coatings.
Less absorbed solar energy means the coated surface heats less strongly.
That can reduce heat radiated and conducted into the surrounding environment.
The colour is visible.
The thermal property is the real infrastructure.
Why the 2°C figure needs to be read carefully
HDB’s current Green Towns material says cool coatings can help reduce ambient temperature by up to 2°C.
That is not a promise that every flat becomes exactly 2°C cooler at every hour.
Actual thermal experience depends on:
- sun exposure;
- wind;
- rain;
- block geometry;
- floor and orientation;
- surrounding surfaces;
- time of day;
- indoor ventilation;
- air-conditioning use.
The figure describes the potential contribution of the town-scale intervention, not a guaranteed thermometer reading inside every bedroom.
The Tampines pilot turned a material idea into estate evidence
HDB and Tampines Town Council tested cool coatings across selected blocks and surrounding surfaces before deciding on wider deployment.
HDB reported that the pilot produced a cooler environment and that residents in coated blocks also experienced reduced electricity consumption as less air-conditioning energy was needed to cool their flats.
That is important because a cooling intervention has two possible returns:
- better thermal comfort;
- lower energy needed to restore comfort.
Islandwide rollout changes cool coatings from experiment to maintenance system
Once HDB commits to cool coatings across existing residential developments by 2030, the question is no longer only whether the material works.
The system now has to coordinate with ordinary estate painting and cyclical maintenance.
That is how climate adaptation becomes durable.
The cooling layer is folded into the long-term upkeep of buildings rather than treated as one special demonstration project.
Shade is often more immediate than reflective paint
A resident walking at noon experiences direct solar exposure immediately.
Moving the same person under a tree, canopy or building shadow changes radiant heat exposure before the ambient air temperature changes much at all.
This is why shaded routes and shaded amenities are central to thermal comfort.
Cooling a town is partly about lowering temperature.
It is also about preventing people from standing in the hottest possible thermal state.
HDB uses environmental modelling before the blocks exist
HDB’s current Green Innovations material describes environmental modelling that simulates natural wind flow, sunlight and shadow casting.
The modelling helps guide:
- block orientation;
- natural wind flow;
- placement of outdoor amenities;
- shaded playground locations;
- placement of greenery in hotter areas.
This is a major planning advantage.
It is cheaper to place a block correctly before construction than to repair a poor thermal layout after thousands of residents have moved in.
Orientation can improve comfort without consuming electricity
A building cannot create wind.
It can avoid blocking useful wind unnecessarily.
Block orientation and spacing influence whether natural ventilation can move through streets, courtyards and homes.
This is passive design.
Once built well, it can provide value every day without a motor, sensor or monthly electricity bill.
Berlayar shows the current integrated model
HDB’s 2025 Berlayar masterplan combines several thermal strategies rather than relying on one feature.
The blocks will use cool coatings and be arranged in a north-south direction where possible.
Environmental simulations of wind flow, temperature, solar irradiance and shadows are being used to optimise natural ventilation, identify shaded playground locations and place greenery in heat hotspots.
Official HDB reference: HDB Unveils Masterplan for Berlayar Estate.
The point is not that Berlayar has many green features.
The point is that each feature acts on a different part of the heat pathway.
Greenery is thermal infrastructure when it is placed deliberately
Trees and planting can provide shade and change the microclimate around hard surfaces.
HDB’s modelling approach uses heat exposure to help decide where greenery can have greater effect.
This is better than spreading the same planting density everywhere for appearance alone.
Greenery becomes infrastructure when placement follows thermal need.
Multi-storey car-park roofs can become cooling landscapes
HDB’s Green Towns Programme also uses greenery and community or allotment gardens on selected multi-storey car-park decks.
This changes a large exposed roof from a heat-absorbing service surface into a more vegetated community layer.
The roof performs several jobs at once:
- covers parked vehicles below;
- supports greenery above;
- reduces heat gain;
- creates visual relief;
- can provide shared community space.
Thermal comfort is a public-health and ageing question too
Heat does not affect every resident equally.
Older adults, young children, outdoor workers and people with some health conditions can be more vulnerable to thermal stress.
A shaded route to the market can therefore matter more to an 80-year-old than to a healthy 25-year-old.
Related owner: Ageing in Place Beyond the HDB Flat.
Cooling outdoors can reduce indoor energy demand
When walls and surrounding air begin from a cooler state, the air-conditioning system has less heat to remove.
This creates a connection between climate adaptation and energy efficiency.
Cooler towns can require less mechanical cooling.
Lower mechanical cooling reduces electricity demand.
Lower electricity demand makes rooftop solar and smart common-area systems more effective as part of the same estate strategy.
More shade is not automatically better everywhere
Dense planting or structures can also interfere with airflow, visibility or maintenance if placed poorly.
The design challenge is not to maximise tree canopy or shade in abstraction.
It is to create shade while preserving:
- ventilation;
- sightlines;
- access;
- security;
- healthy vegetation;
- maintenance routes.
Failure mode: treating cool coatings as air-conditioning for the town
Cool coatings reduce absorbed heat.
They do not refrigerate the outdoor environment.
Thermal comfort still depends on wind, shade, humidity, sun exposure and human activity.
Failure mode: planting greenery where it looks good but cools little
Decorative planting has value.
Thermal planting should follow heat exposure and pedestrian use.
The hottest route used by the most vulnerable residents may deserve priority over the most photogenic location.
Failure mode: measuring the town only by average temperature
Residents experience microclimates.
One playground can be shaded.
Another can sit in direct afternoon sun.
One path can channel wind.
Another can be still and exposed.
Good heat adaptation has to resolve those local differences.
A better HDB heat-resilience test
- Where does the strongest solar load fall?
- Which building surfaces absorb that load?
- Where do residents spend time outdoors?
- Can cool coatings reduce surface heating?
- Can trees, canopies or building shadow protect key routes?
- Does block form preserve useful wind flow?
- Is greenery placed where heat exposure is highest?
- Do the interventions reduce the need for mechanical cooling without harming ventilation or maintenance?
Follow one hot afternoon
The sun strikes an HDB facade.
A reflective coating sends more solar energy away instead of storing it in the wall.
At ground level, trees shade the pedestrian route.
The playground sits in a location chosen through shadow modelling.
Block spacing allows wind through the precinct.
The resident still knows it is Singapore.
The town has simply removed several unnecessary layers of heat from the journey home.
The deeper housing principle
Climate adaptation is strongest when it changes the default environment instead of asking every household to defend itself privately.
A resident can buy a stronger air-conditioner.
The town can also reduce the amount of heat that reaches the resident in the first place.
The deepest answer
Cool coatings, shade and greenery reduce heat stress in HDB towns by acting before heat becomes an indoor cooling bill.
Reflective surfaces absorb less.
Shade blocks direct exposure.
Good orientation keeps air moving.
Greenery moderates exposed spaces.
The result is not a cold town.
It is a town that wastes less energy becoming hot.
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