Following our previous blog “Some Common Questions Encountered When Performing a Commercial EPC Assessment Part 1” click here if you missed it, we cover more FAQ’s when it comes to performing a commercial EPC, and the associated EPC costs and commercial EPC regulations


Which EPC is required if a building’s use changes, Commercial or a Residential EPC?

If a building is being advertised as a commercial unit for sale or let and has the potential/planning permission for conversion into residential use, it needs a commercial EPC as this must reflect the current building (being advertised), anything else would be a predictive assessment. A residential (domestic) EPC would be required after the conversion as required by Building Regulations. The energy assessor cannot carry out an assessment on what might happen, only what currently exists.

Can owners choose to have an EPC produced for the entire building?

Where a building is being sold or let as a whole, an EPC can be prepared for the entire building, even if it is divided into parts that have been designed or altered to be used separately. However, this overlooks the overriding requirement that a separate EPC must be supplied for any dwelling with its own entrance. If the entrance is via an office/shop, then it should be assessed with the rest of the building. If a multi-tenanted building is being sold as a whole, and it has different HVAC systems, then it is usually more beneficial to produce separate EPCs for each unit as these can be used if any tenants change over the next 10 years.

How many EPCs are required for a business centre or multi tenanted building?

If a building has a common HVAC system, government guidance states that an EPC may be prepared for the whole building and a single unit EPC may be based on an assessment of a similar representative unit within the same block. However, the representative units should all be in the same building/block and deciding whether one unit is representative of another, and therefore if the data can be reused, is down to the judgment of the assessor.

Case study – When does one unit accurately reflect another?

An EPC for a large business centre. Before starting, the client asked if we would produce an EPC on one of the units and use this data to represent the other 23 offices, as several office suites were up for let. After discussions with the site maintenance engineer, we found there were two plant rooms with different Heating, Ventilating & Air Conditioning (HVAC) systems servicing various parts of the building, meaning more than one EPC was required. It became clear that each office was not representative of another and individual EPCs were required because:

Commercial EPC for Business Centre

Figure 2 – Illustration of the Various EPC ratings within a typical business centre

• offices had either compact fluorescent, tungsten halogens or

fluorescent lights

• various lighting ballasts were installed – some offices had standard

ballasts while others had high frequency ballasts along with various

types of fluorescent lamps (T5 to T8)

• external glazing varied between office suites within each floor

• office orientations varied

• office designs varied, e.g. some open plan, others cellular

• office facilities varied, e.g. kitchens and toilets were in tenant areas or communal parts, some had data communication rooms and there were various types of hot water systems within each unit.

After completing the EPC assessment on the whole building, we modeled each office individually and the ratings were varied (see Figure 2). There were also differences where HVAC was being supplied from the same system. Where individual office suites were up for let, individual EPCs were needed as the ratings were different to the one for the whole building.

The EPC ratings would have been incorrect if we had used the data from one of the offices to represent them all. For one unit to be representative of another, the age of construction, materials, the activities / floor areas would have to be the same, along with the orientation and the position within the building, types of glazing / rooflights and glazing areas, type of HVAC systems, hot water systems, insulation, and all the building fabric quantities must all be consistent. Generally, the best option is to have separate EPCs prepared where different units have different HVAC systems.

It is certainly not correct to only have one EPC produced for each building if the common use of the term ‘building’ is applied, i.e. to mean the entire structure, which may house many separate units.

If you have any further question relating to commercial epc’s please contact our London office.