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New Building Regulations to come into force in June 2022

Under new building regulations, CO2 emissions from new commercial buildings, including offices and shops, must be reduced by 27% under new rules announced by the government to help the country move towards net zero.

In a government statement, which identified that heating and powering buildings accounts for 40% of the UK’s total energy use, the installation of low carbon technology, such as solar panels and heat pumps, was identified as a core opportunity to help cut emissions – “lowering the cost of energy bills and helping deliver the UK’s climate change ambitions.”

All new residential buildings, including care homes, student accommodation and children’s homes, must also be designed to reduce overheating, making sure they are fit for the future and protect the most vulnerable people.

These new Building Regulations, which set the standards in England for the design, construction and alteration of buildings, follow a public consultation and will come into effect from June 2022.

The intent is that the new building regulations will raise standards and will “pave the way for the Future Homes and Buildings Standard in 2025,” which will address making sure new builds are net zero ready, avoiding the need for retrofit.

There will be a six month period before the new regulations come into force on 15 June 2022. Transitional arrangements are in place which means that if a building notice, initial notice, or full plans for building work are submitted to a local authority before 15 June 2022, then provided the building work commences by 15 June 2023, work on that individual building is permitted to continue under the previous standards.

Useful links to the New Building Regulations  

Conservation of Fuel & Power Volume 2: Buildings other than dwellings

Overheating

Building Regulations for Commercial Hot Water

Committed to raising the energy performance of buildings, the government has now concluded the second of a two-stage consultation on the Building Regulations (Conservation of fuel and power) for England & Wales. This consultation proposes changes to Part L to provide a pathway to highly efficient non-domestic buildings which are zero carbon ready, better for the environment and fit for the future.

These new standards are due to be released in 2025 but will drive interim measures over the next four years for non-domestic buildings as outlined in the Building Regulations: Approved Documents L and F.

These measures outline the expected move away from fossil fuels to low carbon technology for heating and domestic hot water (DHW) and set a more rapid timeline. There is no doubt these new measures will ultimately represent a seismic shift in thinking when it comes to commercial hot water and heating applications, but a buffer has been built in to allow for the development of systems that are necessarily more complex than would be seen in domestic settings. This brings considerable opportunities for developers and specifiers willing to consider both existing and new technologies in order to deliver compliant applications in the next five years.

Whilst a fabric first approach is encouraged, low carbon technologies are being emphasised. This means heat pumps for the broad majority of DHW applications where there is a low heat demand. For commercial properties where there is typically a high heat demand, gas is still allowed while the industry works to develop suitable alternatives.

Hot Water Systems Under Part L For Non-Domestic Buildings

For our current purposes, while we will focus our attention on the provision of DHW for new build non-residential projects. Before we cover that, it is worth noting some of the general requirements for the wider heating systems as these must still be adhered to as part of the overall thermal efficiency of a DHW system.

Each new fixed building service, whether in a new or existing building, must meet the legislated values set out for efficiency. Replacement fixed services must be at least as efficient, either using the same or a different fuel as the service being replaced with matching or preferably better seasonal efficiency.

If moving over to a new fuel system, such as oil or LPG to natural gas, it should not produce more CO2 emissions nor more primary energy per kWh of heat than the appliance being replaced. If ageing renewables such as wind or solar are being replaced the electrical output must be at least that of the original installation, except where it can be demonstrated that a smaller system would be more appropriate or effective. And if work extends or provides new fixed building services energy meters will need to be installed.

When specifying a DHW system, sizing should be based on the anticipated demand of the building (based on BS EN 12831-3). The regulations demand systems not be “significantly oversized,” but we would argue any oversizing will have a negative impact on the efficiency and operational costs of a DHW system. So accurate sizing is critical in terms of delivering an optimal thermal efficiency assessment. That assessment will include the heat generator and any integral storage vessel but will exclude all secondary pipework, fans, pumps, diverter valves, solenoids, actuator and supplementary storage vessels from the calculations.

As a guide the minimum thermal efficiencies for natural gas-based DHW systems, based on gross seasonal efficiency of the heat generator are:

91% Direct fired for a new building with >30kW output*
91% Direct fired for a new building with <30kW output*
91% Boiler efficiency for indirect-fired systems in new & existing buildings
100% assumed Electrically heated new & existing buildings

Adveco carries of range of direct-fired condensing glass-lined water heaters such as the AO Smith BFC Cyclone (97% efficient) and Innovo (98% efficient), as well as an expanding range of stainless steel boilers and water heaters, such as the MD/AD which leverage advanced burner control to drive efficiency even higher (106%). This helps guarantee regulations are met and provides a safety net should regulations tighten in the future.

As with the broader regulations relating to space heating, controls form a necessary element of the new Part L regulations for combustion heated DHW systems. These all must incorporate timer control (independent of space heating circuits) and electronic temperature control.

Additionally, regulations call for fully pumped circulation where compatible with the heat generator for primary hot water circuits. Automatic thermostatic control to shut off the burner/primary heat supply when the desired water temperature is reached, and primary flow if the system temperature is too high for all direct-fired circulator systems, direct-fired storage systems and indirect-fired systems. Direct-fired continuous flow systems should include a heat exchanger flow sensor to control outlet temperatures and detect insufficient flow with burner/heat input shut off. A high limit thermostat is also required to shut off the primary flow if the system temperature is too high.

Point-of-use, local and centralised domestic hot water systems should have automatic thermostatic control to interrupt the electrical supply when the setpoint storage temperature is reached or system temperature gets too high. If there is an over-temperature trip manual reset should be possible.

Local and centralised DHW systems should have both a 7-day time control and the facility to boost the temperature by using an immersion heater in the cylinder.

Instantaneous water heaters should include a flow sensor to control the rate of flow through the heat exchanger. If the sensor detects insufficient flow, it should shut off the electrical input. Plus, a high limit thermostat is required to shut off the primary flow if the system temperature is too high.

Alongside gas, solar thermal is likely to be applied in the notional building unless heat pumps meet 100% of the actual building’s demand. Solar has been used in calculations in the past to overcome the poor fabric performance of a building. But, given the broad majority of heat pumps are currently used for preheat on commercial DHW applications, at most offsetting 70% of the energy demanded, solar thermal has a valid role to play and it’s a proven sustainable technology. Our expectations are for commercial DHW systems to continue in a familiar manner for the near to mid-term, with gas appliances used to provide cost-effective supply, especially during grid peak hours. Heat pumps and/or solar thermal will be deployed to provide preheat to that system.  As efficiencies improve and higher water temperature (more than 60°C) are achieved through heat pumps we see gas appliances slowly being phased out unless they can be replaced with green gas (hydrogen) alternatives. This naturally leads to the provisioning of hybrid systems for the coming decade, optimising a mix of current technologies that address the latest regulations, reduce emissions and crucially deliver value for money with lower operational costs.

One final observation on the implication for the specification and installation of commercial DHW relates to completion requirements. Part L tightens the commissioning requirements to reduce the gaps in performance over design and is intended to deliver improved project handover with accurate energy usage predictions. As a result, we can expect to see revisions of commissioning processes across the industry to help streamline delivery and speed up handover, crucial if government roll-out targets for low carbon technologies to achieve Net Zero by 2050 are to be met and superseded by commercial organisations.

Sources

https://www.gov.uk/government/publications/building-regulations-approved-documents-l-f-and-overheating-consultation-version

* Product standard BS EN 15502-2-1:2012 for gas-fired boilers and appliances of a nominal heat input not exceeding 1000 kW / BS EN 89 gas-fired storage water heaters for the production of DHW