A Government consultation has recently outlined the practicalities for building owners and landlords to reach agreed benchmarks on Minimum Energy Efficiency Standards (MEES). These are not aspirational benchmarks – failure to comply can result in financial penalties and a potential loss in revenue.

Dr. Joe Croft

Head of Environmental and Sustainability

13th Dec 2021

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According to Savills research, most offices need to be upgraded to meet the standard required for a Grade B Energy Performance Certificate. More than one billion square feet of office stock in the UK's major markets, or 87 per cent, needs to be improved to meet the government's 2030 energy efficiency deadlines.

The good news is that there is time to make necessary improvements. To do so, it’s important to understand MEES, how energy efficiency is calculated and what can be done to make a building more efficient.

← Tasman House, Elstree, EPC rating 'A'

Workplace design for energy efficiency
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What are Minimum Energy Efficiency Standards (MEES)?

MEES set a minimum energy efficiency level for domestic and non-domestic private rented properties. They were passed as legislation in 2011 before coming into force in 2018 as part of the Government’s commitment to reach net zero by 2050. This report focuses on non-domestic properties.

When MEES were introduced, building owners and landlords of commercial property had to have an Energy Performance Certificate (EPC) rating of at least E before commencing a new tenancy.

EPCs rate the energy efficiency of a building using grades from A to G, with A being the most efficient. They are required if you rent, sell or construct a property, and in all buildings above 50m2.

From 1st April 2023, all buildings must have an E rating or better even if there are no changes in tenancy. The bar will be raised to a C rating in 2027, and a B rating in 2030.

Landlords must start planning now as the process to energy efficiency can be a long and sometimes complex one. The first step is to understand EPCs.

Diagram timeline for MEES
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What are Energy Performance Certificates (EPCs)?

The Government introduced EPCs as a way to benchmark the energy efficiency of a building. Though they can be considered a somewhat crude assessment, they do provide a standard for all buildings to be assessed against.

They have been a reasonable success, otherwise future goals wouldn’t have been set, and have driven investment into buildings.

EPCs are determined by accredited assessors who use approved software to measure various aspects of a building's energy efficiency to get an end score, which translates to a grade. For example, a score of 0 – 25 is an A, while a score of 150 or more is a G.

Building owners should provide as many metrics as they can to assessors. While default values can be used to benchmark against, they assume the worst so will almost certainly lead to a worse final EPC rating.

The cost of an assessor can vary depending on the building. Some assessors with lower rates may save time by using default values which will result in a poorer score, so it may be worth paying more for an assessor that you know will do a thorough job. Assessors can also run future iteration models to ensure that the cumulative benefit of any changes has the desired effect.

EPCs are valid for 10 years. Considering that the required grade will be rising every few years this decade, building owners should aim for a B sooner to avoid having to get a new EPC for each letting or lease event.

← Cally Yard, London, EPC rating 'A'

Offices assessed for EPC
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How to improve an EPC rating

EPCs are assessed through two main factors – building fabric and building services.

  • Fabric relates to the construction make-up of a building, such as structural frame, floors, internal and external walls, glazing and the roof.
  • Building services is concerned with the provision of heating, cooling, lighting and electric power to the building.

New builds can aim for Passivhaus certification, which has the potential to vastly reduce the energy needed for heating and cooling by using enhanced building fabric parameters and energy efficient building services.

Clarendon Road, Watford, EPC rating 'B' →

Design for sustainable office services
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Passivhaus also offers certification for refurbishment of existing buildings via its EnerPHit standard. EnerPHit has relaxed standards with the acceptance that the existing architecture of some buildings might make Passivhaus impossible to achieve.

Passivhaus and EnerPHit standards can be met via a number of form, fabric and fuel measures, including:

  • Accurate design modelling for new builds
  • High levels of insulation
  • Windows with insulated frames
  • Airtight fabric
  • Ventilation systems with efficient heat recovery

For owners and landlords that are unable to engage with Passivhaus, there are plenty of other ways to work towards an improved EPC rating.

← Tasman House, Elstree, EPC rating 'A'

Office design for maximum sustainability
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Improve EPC rating: Building Fabric

Insulation is arguably the area that can have the biggest impact when looking at improving energy efficiency. Internal insulation can be used for solid brick or metal-clad properties. Cavity walls can be an easy win for improving energy efficiency if they don’t have any insulation.

It’s important to insulate the roof, as a house with no roof insulation will lose about a quarter of its heat. It’s harder to put a figure on commercial properties as they vary so much, from office buildings to warehouses, but it’s safe to assume that a roof with poor insulation will impact overall energy efficiency.

Glazing is another fabric measure to consider, especially in buildings that have a lot of glass. Double or triple glazing is essential to help retain heat in a space.

Airtightness can be a deceptively difficult issue to address, depending on which part of the building is experiencing air leakage. Thermographic studies are used to establish where a building is losing heat. However, access can be a barrier if the location is hard to access. During a refit, work with a designer to ensure that all doors and windows are a tight fit.

Cally Yard, London, EPC rating 'A' →

Improved office insulation and glazing
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Improve EPC rating: Building Services

A great way to improve an EPC rating is for a building to generate its own energy on site, for example through solar panels.

Smart systems can be implemented to ensure that lighting automatically switches off when a space is vacant and is dimmed in areas and times of high levels of daylight. Similarly, ventilation systems can be upgraded to include demand driven control. This will be especially useful considering that many buildings may be below full occupancy for the foreseeable future.

Heating and cooling units can be upgraded to variable refrigerant flow (VRF) units. These are highly customisable and can be configured to have room-specific temperature zones.

Tasman House, Elstree, EPC rating 'A' →

Smart office design building services
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It goes without saying that LED lighting is a critical step. It can be worth having a full lighting design carried out as part of a refit as this can flag up where lighting is being over specified. For example, sometimes there are more light fittings in a meeting room than are required to generate the necessary levels. So, some fittings can be removed, saving energy, while still providing good lighting.

These suggestions give a broad overview of what needs to be considered for an improved EPC rating and reducing energy consumption and the associated carbon emissions. As mentioned earlier in this report, it’s important to find an assessor that will be able to support the process by offering expert guidance. Partnering with a fit out company that is knowledgeable about the factors impacting EPC ratings is just as critical.

There will undoubtedly be challenges along the way, but most can be overcome with advanced planning.

←Wren Court, Bromley, EPC rating 'B'

Improving energy efficiency in office design
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EPC rating challenges: how to overcome them

Every building will have a different EPC scope depending on its size, build, current rating and aspirational rating. We have identified eight common challenges and how to overcome them.

1. Form

As form is related to the orientation and layout of a building, there’s very little that can be done to address this during a fit out or refurbishment project. Owners and landlords will need to focus on the building fabric and building services. It can also help to work towards EnerPHit certification, which accounts for the complexities of addressing form in an energy efficiency project.

2. Default values in EPC assessments

Default values assume the worst, so they are best avoided during an assessment. This might not be possible for every metric if the data does not exist. Work with an EPC assessor that will ensure they avoid default values wherever possible. This might lead to a higher cost for the assessment, but if it results in a better end score, then it’s money well spent. Furthermore, you’ll also have the benchmark data for future assessments.

Wren Court, Bromley, EPC rating 'B' →

Flexible energy efficient office design
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3. Buildings with lots of glass

Big, tall glass buildings can be among the hardest to improve – the limited ability to insulate them removes a key method of reducing heat loss. Owners will have to focus efforts on other areas, such as glazing, air tightness and efficient fuel systems, such as lighting and ventilation.

4. Structural costs

Solar PV are a great way for a building to produce its own energy. However, solar panels are heavy and some buildings may need structural work to support them. This can get expensive so must be taken into consideration before any solar projects go ahead.

←Wren Court, Bromley, EPC rating 'B'

Communal glazed area well insulated
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5. The UK Power Network

Many owners might plan a wholesale switch to electric as part of their energy efficiency plans. However, they will need to work with the UK Power Network (UKPN) to ensure that the incoming supply will have capacity. The UKPN is the only group to deal with and the process can take a long time, so owners must plan and engage well in advance. Failure to do so could delay the project and cause a building to miss a MEES milestone.

6. Global warming potential of refrigerants

Global Warming Potential (GWP) is a measure of how destructive a climate pollutant is. Carbon dioxide has a GWP of 1 R410a, a common refrigerant in commercial spaces, has a GWP of 1,890. It is only a small amount of product in the grand scheme of a commercial space, but it can still have a big impact on an EPC score. R32 is an alternative and has a GWP of 677, which is significantly lower.

Cally Yard, London, EPC rating 'A' →

energy efficient flexible office design
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7. Disruption to tenants

As all buildings must have a minimum of an E rating by April 2023 regardless of whether or not there is a change in tenancy, there will have to be work done while a space is occupied. This can be particularly tricky in a building with multiple tenants. Owners and landlords will need to engage with occupants, explain why work is being carried out and try and agree on timelines that will be the least disruptive.

8. Planning and timelines

With so much to consider it may be overwhelming to plan and manage the project. The best time to start planning is now, even if a space is already at an E rating. To get to a B will take time, money and effort so even if work is not urgent, starting the preparation now will make the process much easier.

← Clarendon Road, Watford, EPC rating 'B'

The benefits of an energy efficient building

Now that the Government has announced the future MEES benchmarks, energy efficiency is non-negotiable. However, there are other benefits to a high EPC rating. By striving for a high rating now, owners and landlords can stay ahead of future requirements. It may be that the Government announces more stringent requirements or adjusts the ways in which EPC ratings are calculated to make the higher ratings harder to achieve.

Attaining a high EPC rating now will avoid any nasty surprises down the line. There is also evidence that green buildings are a more valuable asset. Last year, JLL reported that buildings in central London with an A or B EPC rating achieved a rental premium of 10 per cent, and that green buildings are less likely to sit empty. These findings act as a useful carrot to the stick of the Government MEES regulations. But whichever way you look at it, the countdown is now on to achieving a B rating.