The UK Net Zero Carbon Buildings Standard Guide: Part 6: Fossil fuel free

The standard is written from the position that fossil fuels should not be used within buildings by default. If a project burns fossil fuels for space heating or producing hot water, it cannot be verified as being “Net Zero Carbon aligned”. However, the standard does not prohibit the use of fossil fuels in certain scenarios.

Scenario 1: Outside the scope of the Standard

There are certain energy uses which are excluded from the scope of the building operational energy assessment, and are therefore not covered by the requirement to be fossil fuel free. They are:

• EV charging (as EV charging loads are considered separate from the building loads)
• Heavy process loads
• External lighting and external services
• Energy used within car parks

It is unlikely (though not impossible) that a building would serve these energy uses from fossil fuel sources.

Scenario 2: Exemptions

In addition to the items which are outside of scope, the standard allows the use of fossil fuels in the below circumstances:

• Emergency/life safety systems
• Essential systems in buildings whose failure would have high consequences for loss of human life, or that has very great economic, social or environmental consequences. Examples include hospitals, power plants, sports stadia
• Essential systems in data centres, once reliance on fossil fuels has been minimised
• Construction processes

Aspects we think work well

• We agree that burning fossil fuels has no place in buildings for their everyday functions, such as for providing space heating and hot water production.
• We agree that exceptions should be made for certain scenarios, in particular life safety systems, which often require diesel for provision of a secondary power source and for which alternatives are limited.

Aspects recommended be considered for further development

• Backup and peak lopping power supplies for non-life safety systems could be considered compatible with a Net Zero Carbon future. For example, heat pumps sized to 100% of the building peak heat load would be oversized for most of the year and would require significant electrical infrastructure both in the building and upstream in the grid. Whereas heat pumps sized at 50% of the peak load could cover 95-99% of the annual load, with gas boilers providing additional heating at peak load conditions.
• Whilst we agree that currently it would be difficult to prohibit the use of fossil fuels during the construction of a building, at some point the diesel-driven machinery which is generally used to construct buildings will need to be replaced by alternatives. A significant part of the UKGBC’s Whole Life Carbon Net Zero Roadmap was reductions in site emissions – requiring an 80% reduction by 2050. Reporting of site diesel consumption (without targets) would help highlight best practices.
• Although the focus of the standard is currently fossil fuels, it is worth noting that burning biomass emits higher carbon emissions per unit of energy delivered and also produces other significant pollutants. We would advocate that the burning of any substance, whether fossil fuel derived or otherwise, should be prohibited in buildings which are Net Zero Carbon aligned. 

Max Fordham has a long history of designing projects which minimise and avoid the use of fossil fuels for the production of space heating and hot water. Some of our more recent projects include:

• The multiple award-winning Bluebird project, which utilises heat pumps to serve a series of domestic dwellings for the homeless charity Homeless Action Resource Project. 
• The CIBSE Building Performance Project of the Year, Ravelin Sports Centre, which uses 10% of the energy of a traditional leisure centre.
• Sherborne Abbey, where heat pumps have been incorporated holistically into a heritage building to reduce gas consumption.