RICS – The big changes…

RICS – The big changes… 753 565 Greengage Environmental
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RICS v2 – What are the most important developments to the whole life carbon assessment methodology?

The 2nd edition of the RICS Professional Statement (PS) guidance on Whole Life Carbon Assessment for the Built Environment was released at the end of 2023 and came into effect from yesterday, 1st July 2024 . This means that all assessments undertaken and planning applications submitted after this date will be subject to these new regulations.

The RICS PS 1st edition has become the de facto standard against which all UK whole life carbon assessments (WLCAs) are undertaken and the practice of measuring embodied carbon has developed significantly since its initial release in 2017. The industry itself has changed greatly, with the GLA having incorporated embodied carbon targets into its reporting requirements for major developments since 2020 and other local authorities across the country beginning to follow suit. There is also a national drive in the form of ‘Part Z’, to get embodied carbon integrated into UK Building Regulations. As such, the PS 2nd edition contains some comprehensive changes compared to the 1st edition and this article focuses on some of important developments to the standard that should aid in driving the advancement of the standard and improving overall carbon accounting.

Figure 1 Building and infrastructure life cycle stages and information modules (adapted from EN 15978, EN 17472 and EN 15643, with additions to illustrate biogenic carbon).

RICS v2 Lifestages
¹ https://www.rics.org/profession-standards/rics-standards-and-guidance/sector-standards/construction-standards/whole-life-carbon-assessment
² https://part-z.uk/

Demolition emissions

Following the embodied carbon reduction hierarchy, the first and most significant action involves ‘building less’, which is meant to encourage retrofitting existing buildings as the preferred development option. In utilising the embodied carbon already emitted from those materials, it avoids the need to replace the existing materials and results in significant carbon savings.

However under the PS 1st edition, the embodied carbon emissions associated with demolition were excluded from assessments on the grounds of them having being “often decoupled from new construction projects, hence the responsibility for any emissions arising from demolition is not necessarily solely attributable to the new build project.” This has changed within the 2nd edition and follows guidance issued by the GLA, requiring a flat emissions factor to be applied to the demolished floor area where more accurate figures are not known, and updated at a later date. Overall, this should better encourage developers to opt for a ‘retrofit first’ mentality if demolition comes with a preloaded embodied carbon penalty.

Pre-construction emissions

Whilst typically expected to have much lower direct environmental impacts compared to the remaining life stages, the inclusion of pre-construction emissions within the reporting scope demonstrates the holistic and comprehensive approach to ensuring that all emissions associated with the design and construction process of assets are captured. These emissions include emissions associated with preliminary studies; site surveys, including travel to and from the site; product/material tests or ground investigations.

Where sites are located away from the asset owner or design teams, this might include elements such as air travel, which have previously been overlooked but should always be considered and included within an asset’s total embodied carbon.

Operational carbon emissions

Under the 2nd edition, the level of detail required for reporting operational energy emissions has increased, now requiring operational energy modelling be reported via a local operational energy estimation methodology, such as CIBSE TM54, NABERS, ASHRAE Standard 90.1, the Passive House Planning Package (PHPP), or other local equivalent methodology. As such, this renders Part L calculations as incompatible and must not be used “under any circumstances, as they are not a prediction of energy consumption,” and will therefore amount to the operational energy emissions reported being of a much more realistic and accurate standard.

The assessment scope formerly required assessments to “include all energy use regulated as per Part L of the Building Regulations,” and unregulated emissions included where feasible. However, it is now a requirement to ensure that the full list of requirements, as listed within Table 21 of the standard and including unregulated energy loads, are reported, in addition to reporting the energy from on-site renewables and the electricity grid separately. These include:

  • Heating (B6.1)
  • Domestic hot water (B6.1)
  • Cooling (B6.1)
  • Pumps (B6.1)
  • Lighting (B6.1)
  • Transport systems in buildings (B6.2)
  • Cooking and catering (B6.2)
  • Plugs loads (B6.3)
  • Specialist equipment (B6.2)
  • Mechanical ventilation (including all fans, filtration and heat recovery) (B6.1)
  • Humidification (B6.1)
  • Security and controls (B6.2)
  • Emergency use and maintenance hours (B6.2)
  • Other uses (B6.1)
  • On-site generation (generally photovoltaic) (B6.1)

Overall, operational energy carbon factors have been given an overhaul, from the flat use of SAP 10.2 and instead three sets of carbon factors have been established, dependent upon the needs of the modelling and the stage of the project. The operational energy emissions captured should also now encompass the full scope of operational emissions within the energy supply chain. As such, it is expected that the following supply chain emissions should also be included within the final total presented:

  • Direct emissions associated with energy generation (scope 2), distribution (T&D/scope 3) and use (scope 1, e.g. combustion);
  • Indirect emissions associated with energy generation and distribution (WTT/scope 3); and
  • Indirect emissions associated with the embodied carbon of the infrastructure needed to generate, distribute and store the energy (scope 3).

Finally, energy from on-site renewables and the electricity grid must now be reported separately, to better assess whether the carbon benefits are included within the WLCA or not, dependent on whether the energy is used onsite or exported to the grid. In total, there are three categories of on-site renewable energy generation accounted for:

  • Energy that is generated onsite and used onsite at the time of generation;
  • Energy that is generated onsite but not used at the time of generation, and is therefore exported to the grid. For the purposes of the WLCA, it is assumed that this is reimported at a different time in the year, so the carbon benefit is captured in the WLCA; and
  • Additional energy that is generated in excess of the annual energy consumption of the building and exported to the grid.

Decarbonisation scenarios (material & energy)

The draft GLA assessment methodology issued in 2020 previously factored in the grid decarbonisation and required two sets of results to be produced; one following the business-as-usual carbon factors set out by SAP and another following a grid decarbonisation factor and applying this to the in-use material and operational energy emissions. This was later dropped upon the release of the methodology final version, however RICS v2 has revisited this idea by also seeking to apply the decarbonisation figure to the fugitive refrigerant emissions (B1.2); B2-B4 emissions; and refurbishment, excluding biogenic carbon only (B5) emissions, on the assumption that materials used in these life cycle stages will be produced under future decarbonised carbon factors.

This approach more accurately uncouples assessments from the fixed carbon factors and more appropriately aligns them with the reality of the decarbonisation of the grid. It should be noted that whilst the rate of decarbonisation cannot be guaranteed, its inclusion factors this into the future decarbonisation of, importantly, both materials and energy, and applies the most accurate forecasts available in the form of the Future Energy Scenario (FES) falling short scenario. The specification of the falling short scenario uses the worst-case scenario so as to not under report the carbon emissions.

Addressing uncertainty in WLCAs

In response to the draft version of the PS 2nd edition having been released, the ‘UKGBC Embodied Carbon – Improving your Modelling and Reporting’ report released a set of variance ranges to be applied to each RICS category at each design stage. The RICS 2nd edition now acknowledges the potential to use these variance factors, or alternatively sets out its own methodology to establish a WLCA uncertainty factor based upon the following components:

  • A contingency factor based upon the project phase – applied to all modules A-D;
  • A carbon data uncertainty factor based upon the representativeness and quality of the carbon data used for materials – applied across modules A1-C4; and
  • A quantities uncertainty factor based upon the expected accuracy of the quantities data being used – applied across modules A1-C4.

These component parts produce a % uplift figure, of which the sum of all parts can be applied to the figures reported in the RICS reporting template.

The inclusion of this uncertainty variance factor acknowledges that, especially during the early design stages, not all design information will be available and sets a consistent standard by which to account for these uncertainties across all projects, preventing as yet to be confirmed design details from being omitted and misrepresenting the results.

Other notable mentions

It is worth noting and commending that the new RICS standard has actively acknowledged and considered other existing standards, such PAS 2080, BS 8536, CIBSE TM65 and various European standards, incorporating elements of their methodologies within the new standard. This alignment has in turn created a unanimous standard by which to assess all types of built assets including buildings, infrastructure development and external works, making comparability across assessments much easier.

Finally, the creation of the new B8 life cycle module ‘user activities’ covers “impacts associated with user activities taking place during the operation of building.” Whilst optional to quantify, it is likely to be most significant for infrastructure development where the built asset itself is, in a way, just a shell enabling user activities to take place, such as road enabling the movement of cars. This life cycle stage therefore provides a module in which to robustly report the predicted full impact of any such development and to highlight its true impact, rather than solely focusing on the ‘shell’ development.


The inclusion of each of these measures means that the measuring of embodied carbon has captured a much more holistic view of both the embodied and operational emissions associated with the built environment, closing any gaps in the previous edition of the standard. As such, the development of the PS 2nd edition means that results calculated using this methodology will give a more realistic view of the built environment’s total carbon emissions and should aid in driving meaningful carbon reduction across the industry.

For more information, email cameron.parker@greengage-env.com.

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