Knowledgebase: DCLG Guide to EPC (ND)
Glossary of terms
Posted by Mike Gordon on 22 July 2015 01:05 PM

A building is defined as “a roofed construction having walls, for which energy is used

to condition the indoor climate; a building may refer to the building as a whole or parts

thereof that have been designed or altered to be used separately”.

A stand-alone building is defined as a building that is free standing, i.e. entirely

detached from any other building.

The total useful floor area is the total area of all enclosed spaces measured to the

internal face of the external walls, that is to say it is the gross floor area as measured in

accordance with the guidance issued to surveyors:

a. the area of sloping surfaces such as staircases, galleries, raked auditoria, and tiered

terraces should be taken as their area on the plan; and

b. areas that are not enclosed such as open floors, covered ways and balconies are


Buildings that are industrial sites and workshops with low energy demand. These

include buildings, or parts of buildings designed to be used separately, whose purpose

is to accommodate industrial activities in spaces where the air is not conditioned.

Activities that would be covered include foundries, forging and other hot processes,

chemical process, food and drinks packaging, heavy engineering and storage and

warehouses where, in each case, the air in the space is not fully heated or cooled.

Whilst not fully heated or cooled these cases may have some local conditioning

appliances such as plaque or air heaters or air conditioners to serve people at work

stations or refuges dispersed amongst and not separated from the industrial activities.

residential agricultural buildings with low energy demand include buildings, or parts

of buildings designed to be used separately, that are heated for a few days each year to

enable plants to germinate but are otherwise unheated.

A dwelling means a self-contained unit designed to provide living accommodation for a

single household. This would imply that it does not share kitchen and bathroom facilities.

A non-dwelling is a building that is not a dwelling, such as retail units and offices.

If a dwelling has been altered to enable parts to be used for industrial or commercial

purposes (e.g. a workshop or an office), it should be treated as a dwelling if the

industrial or commercial part could revert to domestic use, without significant alteration,

on change of ownership. This could be the case if:

a. there is direct access between the industrial or commercial space and the living

accommodation; and

b. both are contained within the same thermal envelope; and

c. the living accommodation occupies a substantial proportion of the total area of the

building (e.g. a small manager’s flat in a large domestic building would not mean the

whole should be treated as a dwelling).

Significant alterations are those alterations that are covered by the Building Regulations.

Rooms for residential purposes are not dwellings. A room for residential purposes

means a room, or a suite of rooms, that is not a dwelling house or an apartment and

that is used by one or more persons to live and sleep and includes a room in a hostel,

an hotel, a boarding house, a hall of residence or a residential home, whether or not

the room is separated from or arranged in a cluster group with other rooms, but does

not include a room in a hospital, or other similar establishment, used for patient

accommodation. For the purposes of this definition, a cluster is a group of rooms for

residential purposes that is:

a. separated from the rest of the building in which it is situated by a door that is

designed to be locked; and

b. not designed to be occupied by a single household.

Level three and level four buildings may both be assessed using the simplified

building energy model methodology. Currently the only distinction between these two

levels is on the basis of heating, ventilation and air conditioning (HVAC) systems.

Level three buildings include frequently occurring characteristics such as simple

heating systems, simple natural ventilation and small comfort cooling systems. Level

three does not require the candidate to demonstrate competence in new build.

Frequently occurring characteristics are defined in the national occupational standards

in terms of heating, ventilation and air conditioning, fabric and lighting. (i), (ii) and (iii)

cover heating, ventilation and air conditioning:

(i) simple heating systems (Boiler Systems <100kw)

(ii) simple natural ventilation

(iii) small comfort cooling systems (up to 12kw)

We interpret:

(i) to refer to the size of the total boiler system, so that two linked boilers of 75kW is

level four. Where the heating is not from boilers, we take it to refer to the size of the

individual heater

(ii) to mean opening windows and basic mechanical ventilation (extract tab only)

(iii) to refer to the total for more than one unit (as per boilers). So level three includes

split systems cooling one room or, say, one shop with display and store room cooled by

one unit

Frequently occurring characteristics defined in the NOS (at (iv) and (v)) also provides

definitions based on fabric and lighting, but they are not currently applicable (since they

not defined in the approved methodology):

(iv) typical fabric as defined in the approved methodology

(v) typical lighting systems as defined in the approved methodology

Level four buildings are all buildings that have any heating, ventilation and air

conditioning services that are not defined in the ‘frequently occurring’ list. In practice the

following would be classified as level four heating, ventilation and air conditioning:

• linked boilers totalling >100kw

• multi-split cooling systems and VRF systems

• central air conditioning: AHU, all-air, air/water, chillers

Simplified building energy model is a computer program that provides an analysis of

a building’s energy consumption. The tool is designed to cover buildings that are not

dwellings. It has been adopted by government as part of the UK national methodology

for calculation of the energy performance of buildings. It is also used to produce

consistent and reliable evaluations of energy use in non-domestic buildings for building

regulations compliance and for building energy performance certification purposes

Dynamic simulation model is a software tool that models energy inputs and outputs

for different types of building over time. In certain situations, the simplified building

energy model methodology may not be sophisticated enough to provide an accurate

assessment of a building’s energy efficiency. In these cases government approved

proprietary dynamic simulation Models may be used.

Standard assessment procedure is the government approved methodology for the

energy assessment of dwellings. The current version of has been adopted by

government as part of the national methodology for calculation of the energy

performance of buildings. It is used to demonstrate compliance for dwellings with Part L

of the current Building Regulations in England and Wales.

Reduced data standard assessment procedure is the government approved

methodology for the energy assessment of existing dwellings. A full Standard

assessment procedure assessment requires many data items that cannot be seen in a

survey or will take too long to collect. This methodology is an industry agreed standard

of data items and a standard way of inferring the missing data.