In the 12 months up to January 2023 gas prices rose by 129.4% while electricity was just over half this at 66.7%. Significant percentages. However, apply monetary values, and a different picture emerges – per kWh (at time of writing) gas is costing domestic customers 10.3p, while electricity is 34p. Similar differentials apply, dependent on tariffs, to commercial customers.
On this basis – it costs more to run electric heaters than gas-fired ‘wet’ systems. But should pence-per-kW be the deciding factor?
Many considerations affect how the most cost-effective heating solution is determined – How the heating is used; the type of building; new-build or retrofit; installation; etc.
For non-domestic situations, such as student accommodation, other determinates arise. Such as occupancy patterns and demand for heat and hot water – these are very different from the domestic scene. Likewise, occupants’ attitude to energy consumption, is different, if they’re not directly responsible for paying the bill.
It’s a common misconception that leaving the heating on at a low level, all the time, works out cheaper than a heat-on-demand principle. In the case of student accommodation this would, for the most time, see empty rooms heated. This heat would dissipate throughout the day with no benefit.
Wet systems with slower heat-up rates and lower heat output are more likely to operate in this way. But the occupant has limited control in raising the temperature on demand.
Electric systems with instantaneous boost, are more flexible and efficient – heating the space only when necessary. While reduction of heat input to empty rooms, and if windows are open, are control features that help to lower operational costs.
A unit of gas maybe considerably cheaper than electricity, but boilers are not totally efficient. Even the most technologically advanced have an ‘energy input to heat output’ conversion rate below 90%, compared with 100% efficiency of electricity.
June 2022 saw the Building Regulations Part L updated. It covers the conservation of fuel and power, and energy efficiency for new and existing buildings. The Standard Assessment Procedure is the methodology used by government to assess and compare the energy and environmental performance of dwellings. The most significant difference is that carbon factors have been changed in the Target Emissions Rate calculations. Illustrations show grid electricity produces 136grams of CO2/kWh compared with 210grams for gas. Electricity now has a lower carbon factor.
New non-domestic buildings require a building automation and control system if they include a heating system of 180kW or greater. A minimum standard is introduced to ensure that new buildings with wet heating systems operate a maximum flow temperature of 55°C, and all space and water heating installations in existing non-domestic buildings must now include controls.
The effect is that electrically heated buildings now comply more easily with the updated regulations. This drive to energy efficiency, and cutting CO2 by 27% compared with 2013 levels, sees consultants prioritising a fabric-first approach. Seeking to improve insulation and airtightness wherever possible.
Installation and maintenance costs are another consideration. Wet systems cost more to install, have the added regular costs of maintenance, boiler servicing and potential risk of leaks. Electric systems have a longer life-expectancy, and failing components are easier to replace without having to ‘drain down’ the system.
So, considering the future direction of building regulations, prioritising fabric-first approaches to building services, capital expenditure, maintenance costs and efficiency – it is understandable that developers of student rooms are choosing the cleaner, greener, easier to install and more efficient electrical solutions that use specialist control systems to prevent energy from being used unnecessarily.