In November 2025 the Cabinet approved Thailand’s third Nationally Determined Contribution under the Paris Agreement. It sets a path to net-zero greenhouse-gas emissions by 2050, with net emissions in 2035 47% below their 2019 level. For a building owner, that turns energy efficiency from a saving on the bill into the first part of a long-term plan, and in a Thai commercial building the air-conditioning is usually the largest user of energy.

The net-zero pathway for a building

Net-zero plans for buildings generally follow the same order:

  1. Measure. Find out where the energy goes, from the meters and the building automation system.
  2. Cut waste. Fix what uses energy for nothing: the air side, controls and schedules, the building envelope.
  3. Make the plant efficient. Chillers, pumps, cooling towers and their controls.
  4. Switch to clean power. Solar on site and renewable electricity.
  5. Offset what remains. With credible carbon credits.

The order matters. Every kilowatt-hour saved in the first three steps never has to be generated, bought as renewable power or offset, so each later step gets smaller and cheaper. It matters for the people inside too: a building that is damp or short of fresh air does not get any healthier when its electricity turns green.

Where the air side wastes energy

Bangkok’s outdoor air is hot and humid for most of the year. A conventional air-handling unit uses one cold coil for two jobs: cooling the air and drying it. To take the moisture out, the coil has to run colder than the room needs, so the chillers make colder water than cooling alone would require, and the room is either overcooled or the air is heated again before it is supplied.

Part load makes it worse. When a room needs less cooling, the coil’s valve closes, the air is no longer dried and humidity drifts up. Rooms that must hold a humidity limit, such as operating theatres, laboratories and archives, then cool the air hard and reheat it, paying for the same energy twice.

Fresh air adds to the load. Buildings need outdoor air for the health of the people in them, and every cubic metre of humid outdoor air brings in moisture that has to be removed.

Air-side optimisation, step by step

Air-side optimisation means giving each space the temperature, humidity and fresh air it needs with the least energy. The main levers are:

  • Measure first. Trend room temperature and humidity, valve positions and supply-air conditions on the building automation system. Chilled-water valves that sit wide open while humidity stays above 60% show where the energy goes.
  • Bring in the fresh air the occupants need. Control outdoor air on measured CO₂, so the building does not cool and dry more humid air than it uses.
  • Separate humidity from temperature. Dry the outdoor air to the dew point the rooms need, and cool the return air with a coil that only handles heat. This is what SMAC does: a latent coil dries the outdoor air, a sensible coil handles the heat, each on its own sensor and valve, and the SMAC Contrologic™ controller balances the two.
  • Raise the chilled-water temperature. Once the cooling coil no longer has to dry the air, it can run on warmer water and the chillers work less hard. Contrologic resets the chilled water to the warmest temperature that still meets the load.
  • Remove reheat. With humidity controlled where the moisture comes in, close-control rooms no longer need to heat the air again.
  • Match fan energy to the load. Air volumes and fan speeds follow what the spaces need.

SMAC’s design guidance puts typical savings at 30–60%: up to 24% of cooling energy from chilled-water reset, up to 20% from better humidity control, up to 15% of fan energy, and all of the reheat in close-control rooms. These are design ranges, not promises, which is why every SMAC project starts with a model of the building’s own loads.

Mould control is humidity control

Mould needs moisture, not heat. In a tropical building it grows where humid air meets a cool surface: on ceilings and in ducts, behind furniture, in store rooms and archives, and in rooms that are used only part of the time. It shows up as musty smells, stained finishes, damaged stock and collections, and complaints about the air, and it comes back after every clean-up while the cause remains.

A system that controls temperature alone cannot stop it, because humidity rises just when the cooling load falls: at night, in cooler weather and when a building is half empty. The lasting fix is to control the dew point of the air entering each space. SMAC dries the outdoor air before it reaches the rooms, so humidity stays under control at part load as well, without overcooling or reheat.

In hospitals the same control keeps operating theatres and isolation rooms within their temperature and humidity limits around the clock.

Results from SMAC sites in Thailand

SMAC has proved itself in buildings around the world since 1999. In Thailand, a corporate head office in Bangkok has run on SMAC since 2003. Clients are described by sector until they agree to be named.

  • 43%less energy

    Corporate head office, Bangkok, since 2003. Outdoor air was raised from none to 10 m³/h per m² of floor while energy use fell. The buildings later earned LEED Platinum.

  • 63%less energy

    Precision fabric factory, Phuket, since 2005. Temperature and humidity held for production on the factory floor.

  • 40%less energy

    Teaching hospital, Bangkok, since 2013. 64 operating theatres, 38 laboratories and isolation rooms, and four dedicated outdoor-air units on one SMAC platform, with no reheat.

  • 30%+less energy, IPMVP-verified

    Gas-pipeline control building and substation, since 2017. SMAC DX with no reheat. Savings verified under IPMVP Option B by a third-party Performance Measurement and Verification Analyst (PMVA).

  • 35%less energy

    Executive housing with VRF. A SMAC DX dedicated outdoor-air unit added to the existing VRF system and tied in over BACnet, without replacing it.

Measured and verified savings, as published by SMAC Technologies (Introduction to SMAC, December 2020). At the control building, the savings were verified under IPMVP Option B by a third-party PMVA.

The investment case

An owner deciding on air-side work wants to know three things: how much it will save, how sure that is, and how it will be proved. A SMAC project answers them in that order.

  • Before you invest. The SMAC Energy Modeller simulates the building hour by hour over a full weather year and compares 23 air-conditioning processes, SMAC among them, on energy use, humidity, mould risk, comfort and carbon, using the building’s own loads.
  • What the physics is worth. On a 500 TR chiller plant at full load, raising the chilled water from 7/12 °C to 12/17.55 °C cuts chiller power from 0.538 to 0.437 kW/TR: 50.4 kW, or 18.7%, less. Over 4,000 full-load hours a year that is about 200 MWh, roughly THB 0.8 million at about THB 4 per kWh and about 95 tonnes of CO₂e at Thailand’s grid emission factor. The savings from removing reheat and drying only the outdoor air come on top.
  • After it is installed. Savings are measured under IPMVP, the International Performance Measurement and Verification Protocol, so the result is a number on the meter rather than an estimate. Through our energy services, the measured savings can pay for the work.

The 500 TR figures are a worked example from SMAC Technologies’ engineering data (December 2020); the operating hours and tariff are assumptions to be replaced with your site’s own.

Air-side work is rarely the most visible part of a net-zero plan, but in Thailand’s climate it is often the part that pays for the rest. Goldmarktech delivers SMAC in Thailand with Carrier equipment. To see what it would save in your building, open the SMAC Energy Modeller or talk to one of our engineers.