New Net Zero Housing Policy in Bristol

If you are an architect and or developer you may be aware of that Bristol City Council is working on an emerging local plan, and it is mooted to contain a commitment to Net Zero Housing.

But is this a big deal? And what will change when this policy is implemented?

Is New Housing in Bristol Net Zero Now?

It is an interesting time in Bristol at present and this may be one of the last reports we write using core Planning Policies like BCS13 (Climate Change) and BCS14 (Sustainable Energy) of the Core Strategy (2011) require developments to follow an energy hierarchy:

• minimising energy requirements,
• incorporating renewable energy sources, and then
• low-carbon energy sources.

They also expect a certain percentage of carbon dioxide emissions from residual energy use to be offset through renewable energy generation (at least 20% according to some interpretations). So no at present you have to only provide a 20% reduction. . . . . but it is not quite as simple as that.

FEE Fi Fo Fum

Back in 1992 the BRE introduced SAP, and in 2009 we saw the emergence of Fabric Energy Efficiency as a new factor within the SAP model.

FEE or Fabric Energy Efficiency was introduced so as to give a separate value for how energy efficient the building fabric is, this may have been to avoid the use of excessive renewables, in order to make up for a poorly insulated house.

As of SAP 2012 the requirements to meet Target Fabric Energy Efficiency TFEE are getting more onerous. So a typical build in trying to meet TFEE will have a very low operational carbon emission rate, perhaps 15.23kg/m2/year. To all intent and purposes this is a very small amount of carbon to offset with renewal energy on site, at which point you would (in an operational sense) achieved a net zero home.

So what will Change when Bristol changes to Net Zero Housing?

The main change will be the consideration of embodied carbon. Up to now in this post we have been considering operational carbon emissions. These are the emissions associated with generating the electricity to run the building.

A typical build with excellent insulation (it has to have that anyway to mett TFEE), a heat pump, and a smattering of solar panels will be carbon neutral, perhaps even slightly negative. So from a operational standpoint very little will change.

But as we have seen in London, and numerous other local authorities  (see LETI) we now must consider embodied (or capital) carbon.

This is not such a huge deal in terms of finding a solution. A build that is slightly carbon negative will pay itself off over its lifetime. But the real kicker is calculating the carbon cost of the build. This will involve some form of lifecycle analysis and this will mean a lot of extra work for Life Cycle COnsultants cuh as ourselves, but is ultimately bad news for anyone submitting a planning application, as it will be an extra cost.

There is also the prospect of having to pay carbon offsets, if you (for example) couldn’t provide renewables. Or were forced to use high carbon construction materials owing to environmental or heritage constraints.

What other Net Zero Housing measures are in the Bristol City Council Emerging Local Plan?

Below is an AI summary from Gemini AI, but we have added commentary in Blue.

Here’s what we know about Bristol’s emerging Local Plan policies for net-zero housing:

Key Principles and Goals:

• Zero Carbon Housing: The council is developing its Local Plan to require Zero Carbon Housing in new developments. This is a significant step up from previous requirements focused on percentage reductions in carbon emissions.
• Climate Resilience: Alongside net-zero carbon, the policies aim to ensure new homes are resilient to future climate change impacts, particularly overheating. This includes design considerations for orientation, ventilation, and thermal mass. There are different grades of overheating assessment there are guide method such as cross ventilation, but also calculated method such as TM19. SAP also includes a simple overheating assessment.
  Energy Hierarchy: The policies will likely continue to follow an energy hierarchy, prioritizing:
  Minimizing energy demand through high energy efficiency standards (fabric first approach). Incorporating on-site renewable energy generation. Utilizing low-carbon energy sources, with a preference for connection to district heat networks where available.
• Whole Life Carbon : There’s a move towards considering the whole life carbon impact of developments, including emissions from construction and materials, although the specifics of targets and offsets are still being developed. – This is the big one. It will add complexity to sustainability reporting. 
  Performance Gap: The council aims to address the “performance gap” by seeking requirements for measured in-use energy consumption to match design performance. – Good idea but how will this be enforced. 
  Monitoring and Transparency: The emerging policies may include requirements for monitoring the energy performance of a percentage of new dwellings in their early years of occupancy and making this information transparent.

Specific Policy Areas Likely to Drive Net-Zero Housing:

• Energy and Carbon Policies (Likely Policy NZC1 and related): These policies will set the overarching targets for carbon emissions from new buildings, pushing beyond national Building Regulations (Part L). They will likely include specific energy performance standards (e.g., maximum energy use intensity, space heating demand) and requirements for on-site renewables.
• Heat Decarbonisation Policies: These will promote the use of low-carbon heating systems, prioritizing heat networks (like the Bristol City Leap network) and heat pumps over traditional fossil fuel boilers. New developments in heat network priority areas will likely be required to enable connection. – Already encouraged through SAP. 
• Sustainable Construction Policies: These policies will address the materials used in construction and may include measures to reduce embodied carbon and promote circular economy principles.
• Climate Change Adaptation Policies: These will ensure new buildings are designed to cope with the impacts of climate change, particularly overheating, through design and green infrastructure.

Current Status and Next Steps:

The Bristol Local Plan is currently in the examination phase. The final consultation on the publication version of the plan took place between November 2023 and January 2024.
The Plan will be submitted to the Secretary of State for independent examination, which is expected to take at least a year.

The Inspector’s report could be received from Spring 2025 onwards, and if deemed sound, the Full Council might adopt the new Local Plan in Spring/Summer 2025.
In the interim:

The current Bristol Local Plan policies (adopted between 2011 and 2014) still apply, which encourage energy-efficient buildings and on-site renewable energy.

Bristol City Council’s Climate Change and Sustainability Practice Note provides guidance on implementing these existing policies and encourages developers to go beyond the minimum requirements, aligning with the city’s net-zero ambitions.

Therefore, while specific adopted policies for net-zero housing are not yet formally in place, Bristol City Council is actively progressing towards their implementation through the emerging Local Plan, with adoption anticipated around Spring/Summer 2025. Developers need to monitor the progress of the Local Plan examination to understand the precise requirements that will be placed on new residential buildings.