Published September 2023
Although new buildings make up a small proportion of overall building stock, it is crucial that they are designed to deliver net zero whole life-cycle carbon emissions. Construction is energy intensive and involves the consumption of many materials, resulting in large GHG emissions. Therefore, a substantial share of the emissions associated with buildings and infrastructure projects is released before the asset is ever used. Unlike retrofitting existing buildings, building from scratch gives public bodies greater control over a building’s embodied carbon and an opportunity to embed excellent building energy efficiency.
Public bodies should refer to the voluntary Net Zero Public Sector Buildings Standard (2021) to ensure good practice for design and construction of new buildings and major refurbished infrastructure projects (see more below). The SSN CCIA task and finish group has created guidance for public bodies on developing their own Climate Change Impact Assessment framework to incorporate the carbon impact of buildings and infrastructure projects into their decision making.
Extending the lifetime of a building by renovation should always first be considered before replacement, as this is often a more efficient use of materials and energy, resulting in fewer GHG emissions. The LETI Retrofit vs Rebuild offers guidance on how to compare whole life carbon for a retrofit versus its demolition and rebuild. The hierarchy for embodied carbon reduction emphasises building less over building clever.
Carbon Management
Quantifying the GHG emissions associated with a building requires a whole life cycle approach. To enable direct comparisons between projects and benchmarks, consistent assessment methodologies and reporting is necessary. An appropriate methodology for managing and minimising whole life carbon emissions resulting from projects should be applied from the earliest possible stage. Whole life costing should be used to make visible the true costs of operational and embodied carbon and allow better informed decisions about both capital and operational expenditure. There are different methodologies internationally acknowledged as best practice approaches for managing whole life carbon for buildings and infrastructure projects. A whole life carbon (WLC) assessment should:
- For building projects, follow the Royal Institution of Chartered Surveyors (RICS) Whole Life Carbon Assessment for the Built Environment guidance. It mandates a whole life approach to reducing carbon emissions within the built environment and sets out specific mandatory principles and supporting guidance for the interpretation and implementation of EN 15978 methodology. This is compatible with the Scottish Government’s Net Zero Public Buildings Standard (see below).
- For infrastructure projects, follow PAS 2080: Carbon Management in Infrastructure. PAS 2080 is a globally applicable standard for managing carbon in building and infrastructure. It looks at the whole value chain and aims to reduce carbon and cost through intelligent design, construction, and use. It’s a key reference document in the UK government’s Construction Playbook that’s increasingly becoming the go-to specification for carbon management in the built environment.
These are discussed further in the Scottish City Region and Regional Growth Deals Carbon Management Guidance for Projects and Programmes (Sept 2021) developed by the Scottish Government for project owners on managing and minimising potential carbon emissions associated with growth deal projects. This guidance uses PAS2080 as its framework and goes on to provide a streamlined system for assessing and prioritising action on carbon within growth deal projects. The guidance is also useful when considering carbon in infrastructure projects, buildings or as part of wider place-based climate plans.
The Net Zero Public Buildings Standard
Building regulations are technical requirements applicable to building work set by the government. There are additional voluntary building standards which quantify the energy performance of a buildings. In collaboration with Zero Waste Scotland and Health Facilities Scotland, the Scottish Futures Trust has developed a (currently) voluntary Net Zero Public Sector Buildings Standard (launched 2021) which Scottish public bodies should refer to to ensure good practice for design and construction of new buildings and major refurbished infrastructure projects. There are hopes that this standard will be regulated in future.
The standard covers 3 key concepts:
- Place
- Carbon: embodied, operational, and other whole life carbon
- Environment: indoor environmental quality and environmental aspects
The NZPB standard places great emphasis on the setting of ambitious targets early in the process and then to measure and ultimately verify these ambitions in-use. The standard applies to the full lifecycle of a project from briefing, development and delivery to the operational stage. It is aligned with the RICS professional Statement and promotes circular design practices. A main standard document sets out principles and approach and is accompanied by a suite of supporting documents (including Pathfinder case studies). Although currently aimed at new build and major refurbishments this work is being extended to look at the existing buildings.
See more information about the Standard here:
- SSN 2022 Conference: Net Zero Public Sector Buildings & Reporting discusses the standard and helpful synergies between it and the PBCCDR
- SSN 2021 Conference: Mott MacDonald’s presentation explaining the NZPBS.
Procurement
Public bodies should use their procurement power to support the decarbonisation of highly emitting steel and cement industries. The Climate Emergency Collaboration Challenge Project report discusses how the University of Edinburgh as a client can work more collaboratively with construction partners to deliver a zero-carbon built environment. It stresses that net zero priorities must be articulated from the outset and project governance must ensure these outcomes are maintained throughout delivery, early engagement and close collaboration with commercial partners is key. It provides further advice applicable to UK universities and public bodies. For further information on procurement, please see our SSN page here.
Improved Building Design
The design of buildings is crucial to heat decarbonisation as this shapes a building’s energy consumption and subsequent emissions for decades. Apart from ensuring buildings have minimal embodied carbon, designs must ensure that new buildings are energy efficient, use decarbonised heating systems. Often, they also include integrating energy generation into buildings such as solar photovoltaics, solar thermal and passive heating via glazing. A building with net zero operational carbon does not burn fossil fuels and achieves a level of energy performance in-use in line with our national climate change targets. No carbon offsets can be used to achieve this balance.
A Fabric First Approach to construction considers the design and materials of a building’s envelope - frames, structure and insulation - in the initial design stages. It prioritises heat conservation rather than relying on decarbonised heat generation. Adopting this approach is critical to reducing energy demand and preparing buildings for zero emissions technologies. This is best achieved through:
- Maximising airtightness
- Increased levels of insulation
- Optimising solar gain through the provision of openings and shading
- Optimising natural ventilation
- Using the thermal mass of the building fabric
Passive house (PassivHaus) is an international quality assured standard and methodology for achieving low energy building design based on the principle of reducing heating demand through a fabric first design. Buildings built to Passivhaus standards use up to 90% less energy for heating and cooling, and up to 70% less energy than conventional buildings. For technical specifications see here, this includes a space heating and cooling demand benchmark of 15kWh/m2/year, which far exceeds current building regulations. Passivhaus building characteristics and examples are shown here.
Material efficiency improvements cover a broad suite of measures that lower energy needs through more efficient use and management of materials. Different material efficiency measures can be applied at the design, production, use and end-of-life stage of the supply chain for each type of good or service. Examples include measures to reduce material demand, use materials or production routes with lower lifecycle emissions and recycling materials at the end of product lifetimes.
Digitalisation is an important enabler of energy efficiency and demand flexibility in buildings. These “smart” buildings benefit from advanced sensing and controls, systems integration, data analytics and energy optimization to actively reduce energy use and demand. The potential energy savings from smart buildings is significant. Basic automated building controls can save 10-15% of energy in commercial buildings. More advanced functionality, such as demand-controlled ventilation, can save an additional 5-10% in energy (World Economic Forum). In addition, grid-interactive Efficient Buildings (GEBs) can reduce energy costs through active demand management.
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