Choosing a water heater? How gas can save you money and your carbon footprint

Those who enjoy taking hot showers at the end of a long day can do so without worrying about their carbon footprint and electricity bills if they opt for gas water heaters.

Such heaters produce significantly lower carbon emissions than their electric storage counterparts, according to a 2023 research study by Associate Professor Lee Siew Eang from the College of Design and Engineering at the National University of Singapore.

The study was done with the support of City Energy, Singapore's only provider of piped town gas.

Every year, electric storage heaters are estimated to emit about 400kg of carbon per user, five times more than gas instant models at 80kg, Assoc Prof Lee found.

The higher emissions are due to the fact that electricity must first be generated, mainly by burning natural gas. Gas heaters skip this extra step, he added.

This means households that switch to gas could cut down their carbon emissions by up to 320kg per user annually.

In addition to being better for the environment, gas water heaters are also more energy efficient, Assoc Prof Lee said on Wednesday (Nov 5) during a City Energy media event at the Landmark Condominium.

The condominium is one of many residential developments that have installed gas water heaters for their units.

He explained that traditional electrical storage heaters experience higher standby losses from keeping large volumes of water heated over extended periods and having to reheat water which has cooled down in the tank.

Standby loss refers to energy wasted by devices when they are plugged in but turned off or in "standby" mode.

Gas heaters, on the other hand, heat water as it flows through — which reduces the amount of energy wasted during storage or reheating, Assoc Prof Lee said.

Households can save $1,200 or more

Households currently using electrical storage heaters that switch to gas heaters can therefore save around $1,200 over the latter's lifespan of about 10 years, showed a study by the National Environment Agency (NEA) in 2019.

From April 1 this year, NEA extended its Mandatory Energy Labelling Scheme (MELS) to household water heaters, with more than 200 water models being registered and rated from one to five ticks on energy efficiency since then. 

These include gas instantaneous, electric instantaneous and electric storage water heaters. 

Out of 21 gas instantaneous heaters that have been registered under the scheme, 16 received four ticks.

Just two out of 68 electric storage models were given the same rating.

From April 2026, models that fail to get at least a one-tick energy rating under MELS can no longer be sold, according to NEA.

Gas heaters must pass thorough safety checks

According to City Energy, water heaters are used in more than 210,000 Singaporean households to date. 

A total of 800 households have switched from electric to gas water heaters since the company started its conversion programme — which allows homeowners to replace their existing appliance with the brand's gas heater within a day.

It also observed an increase in the number of condominium developers opting for gas water heaters in the past three years, with 70 per cent of newly built private homes with town gas connections doing so.

Responding to concerns about the safety of water heaters that use gas, City Energy stated that all gas heaters must go through thorough safety checks before being approved for use in Singapore.

There are also mechanisms installed into such heaters to cut off the gas supply if they overheat. This not only prevents damage to the appliance, but also gas leaks.

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bhavya.rawat@asiaone.com