If we are to strive to improve the carbon emissions and sustainability of commercial interiors, we need to have a set of universal metrics to compare case studies.

These must be quantified, comprehensive, usable by all projects, and relevant.

We have taken a triple bottom line approach. That is, metrics that cover economic, environmental and social sustainability.

Below are the metrics that we will be applying to case studies to the extent that data is available. We welcome your comments and suggestions.

We recognise that this is new to many, including suppliers, so data can be difficult to source and results may be patchy. However, we are strong believers that perfect should not be the enemy of good.

1. Cost per area (£/ft2)

Net Zero Carbon solutions will struggle to be adopted if they cost more than high carbon options. Therefore we suggest this straightforward measure of economic sustainability, for which data is readily available for clients.

2. Greenhouse gas emissions per area (kgCO2e/ft2)

Given the urgent need for action to address climate change, a greenhouse gas emissions metric is pertinent.

Ideally, this should include operational and embodied emissions and cover the entire fit-out lifetime, not just the initial emissions.

However, data is most readily avilable for the initial embodied emissions i.e. the emissions that have gone into creating the interior.

It is noted that GHG data can be difficult to source, so reporting the emissions for different aspects of the interior (build, furniture and HVAC) will enable comparisons at a category level.

3. Percent second life furniture (%)

Furniture creates the greatest carbon emissions over the lifetime of a commercial building.

The Circular Economy is the only way to substantially reduce embodied emissions and all forms of second life (reuse, refurbished and remanufactured) reduce emissions, waste and resource extraction by 60% to 100% compared with new furniture made from virgin resources.

Therefore a furniture-specific metric recording the extent to which the Circular Economy is employed to reduce carbon emissions is warranted, noting that if second life furniture is chosen for a project, there is a high likelihood that other second life products will have been included in a project (e.g. raised flooring panels).

This metric encompasses a range of environmental sustainability dimensions.

The UK Office Furniture Remanufacturing Association (OFRA UK) has established  such a metric and offers a free-to-use mark that See Net Zero will be using.

OFRA UK’s mark

4. Percent locally made/remade (%)

Local production (which we define as made – not just assembled – in the UK) creates British jobs, improves national balance of payments, and improves in-country supply chain resiliance. All of these are desirable social sustainability outcomes.

We suggest reporting local production figures per purchasing category (e.g. loose furniture, flooring, services, building materials). This will mean some figures are available even if data is difficult to obtain for all product categories.

Supply from local SMEs and Social Enterprises creates a range of indirect community benefits and will be included where known.

5. Employment for those furthest from the workforce (hrs)

Social sustainability includes employing those furthest from the workforce.

Specifically, this covers those who are long-term unemployed, disabled, formerly homeless and those at risk of homelessness.

We will only count hours spent in training and work that are paid at the Real Living Wage or higher.

Other indicators of sustainability

Of course, not all metrics will be available for every historical project so we must do our best. However, using these metrics – and the benchmarks that projects set for them – will hopefully encourage more projects to quantify and report on them.

Other indicators of sustainability, both quantitative and qualitative, will be available for some projects. These will be reported where known. Some of these, like BREEAM, NABERS and WELL ratings, are not universally comparable, but do provide benchmarks for those using these accreditations.