25 Oct 2024

Is storage heating more expensive than gas in Singapore?

Introduction

This article aims to compare the costs of operating an electric storage heater versus a gas water heater in a typical Singapore household. The analysis explores energy consumption and costs for heating water for showers, based on assumptions for a household size of four individuals (two males and two females), each showering twice a day.

Parameters Assumptions

The following parameters are assumed based on typical conditions in Singapore:

Incoming water temperature: 28°C

Hot shower temperature: 38°C

For the electric storage heater, the thermostat is set to kick in at 50°C and cut out at 60°C.

For the gas water heater, the temperature setting is 50°C.

Household size: 4 (2 males, 2 females)

Water usage per shower:

Males use 45 litres per shower.

Females use 65 litres per shower.

Shower frequency: Each person showers twice a day.

Electricity (KWH) Computation for Electric Storage Heater

The energy required to heat water can be calculated using the formula:

E = m × c × ∆T

Where:

E = Energy required (in kilojoules)

m = Mass of water (in kilograms, which equals the volume in litres)

c = Specific heat capacity of water = 4.18 kJ/kg°C

∆T = Temperature change (in °C)

To convert the energy from kJ to kilowatt-hours (kWh), use:

1kWh = 3,600kJ

For males (using 45 litres per shower) =

E = 45 × 4.18 × (60°C − 28°C) = 6,019.2 kJ

For females (using 65 litres per shower) =

E = 65 × 4.18 × (60°C − 28°C) = 8,692.8 kJ

Since 1 kWh = 3,600 kJ, we convert the energy to kilowatt-hours (kWh)

Energy for males (kWh) =

6,019.2 / 3,600 = 1.67 kWh

Total energy per day for 2 males (showering x2 daily) =

1.67 × 2 × 2 = 6.68 kWh/day

Energy for females (kWh) =

8,692.8 / 3,600 = 2.41 kWh

Total energy per day for 2 females (showering x2 daily) =

2.41 × 2 × 2 = 9.64 kWh/day

Total energy per day for household (electric):

6.68 kWh + 9.64 kWh = 16.32 kWh/day

Gas (KWH) Computation for Gas Water Heater

The energy required to heat water can be calculated using the formula:

Q = m × c × ∆T

Q = Energy required (in kilojoules)

m: Mass of water (in kg, where 1 liter = 1 kg)

c: Specific heat capacity of water = 4.18 kJ/kg°C

: Temperature change (in °C)

To convert the energy from kJ to kilowatt-hours (kWh), use:

1kWh = 3,600kJ

For males (using 45 litres per shower) =

For females (using 65 litres per shower) =

Since 1 kWh = 3,600 kJ, we convert the energy to kilowatt-hours (kWh)

Energy for males (kWh) =

/ 3,600 = 1.15 kWh

Total energy per day for 2 males (showering x2 daily) =

1.15 × 2 × 2 = 4.60 kWh/day

Energy for females (kWh) =

/ 3,600 =

Total energy per day for 2 females (showering x2 daily) =

1.66 × 2 × 2 = 6.64 kWh/day

Total gas consumption per day for household (gas):

4.60 kWh + 6.64 kWh = 11.24 kWh/day

Comparison of Electric Bills in Singapore

SP Group Bill

Keppel Electric Bill

Cost Comparison Table

Heater Type	Energy per Shower (kWh)	Energy per Day (kWh)	Energy per Year (kWh)	Cost per Year (SGD)
Electric Storage Heater	1.67 (male), 2.41 (female)	16.32	5,956.8	$1,191.36*
Gas Water Heater	1.15 (male), 1.66 (female)	11.24	4,102.6	$820.52**

Table 1: Cost Comparison of Electric Storage Heater vs Gas Water Heater

Conclusion

Is storage heating more expensive than gas in Singapore?

Based on the calculations, the gas water heater is cheaper to operate than the electric storage heater by approximately 31%. This is primarily due to the lower energy consumption required to heat water to 50°C for the gas water heater, compared to the higher energy required for the electric storage heater, which heats water to 60°C. While the energy cost difference is clear, other factors like installation, maintenance, and convenience should also be considered when making a final decision.