Reference
EPC glossary
Plain-English definitions of the terms used on a domestic Energy Performance Certificate and across EPC Benchmark’s aggregate comparisons for England and Wales. Definitions describe what terms mean — they are not advice, and they do not state costs, savings, point gains or legal requirements.
The official Find an energy certificate service covers England, Wales and Northern Ireland; Scotland has a separate service. EPC Benchmark’s aggregate comparison covers England and Wales only, and where a term is specific to that scope it is stated. For an individual property, the authoritative source is always the official register.
A
Aggregate data
- Figures summarised across a group of properties rather than for any individual home. EPC Benchmark publishes only aggregate views — counts, medians, means and band shares — and never address-level or certificate-level records.
Archetype
- A group of homes defined by a shared combination of attributes. On this site the national archetype combines property type and construction age band across England and Wales, and is the closest combined-attribute view published.
Assessment
- The visit and calculation that produce an EPC. An accredited assessor records the property's characteristics — walls, glazing, heating and so on — and the assessment methodology converts them into a standardised score.
Assessor (energy assessor)
- The accredited person who inspects a home and records the data behind its EPC. Comparability between homes depends on the fields the assessor observed and recorded at the time.
B
Built form
- How a building is attached to neighbouring buildings, for example detached, semi-detached or terraced. This is separate from property type, such as house or flat. EPC Benchmark's current four comparison views do not match on built form.
C
Certificate / report
- The EPC itself: a standardised document showing the home's current and potential scores, its recorded characteristics, and the recommendations identified by the assessment. Certificates for England and Wales are published on the official register.
Comparison lens / view
- One published aggregate group that a score can be compared against. EPC Benchmark shows four independent lenses: district all, district by property type, district by construction age, and national type-and-age. They are separate comparisons, not a single combined cohort.
Construction age band
- The range of years in which the assessor recorded the home as being built, such as 1930–1949. Age matters because construction methods and insulation standards changed over time, so age band is one of the grouping attributes in the published views.
Current property / current certificate
- The latest certificate recorded for each valid UPRN in the analysed release. A property reassessed several times appears once, using its most recent certificate. The release contains 19,324,312 current properties.
Current rating
- The score the home received at assessment, from 1 to 100, based on the characteristics recorded at that time. Work carried out after the assessment is not reflected until the home is reassessed.
E
Energy Performance Certificate (EPC)
- A standardised certificate rating a home's modelled energy performance from 1 to 100, grouped into bands A (highest) to G (lowest). EPCs are required in many sale and rental situations in England and Wales. Use the official Find an energy certificate service for England, Wales and Northern Ireland; Scotland has a separate service. EPC Benchmark's aggregate comparison covers England and Wales only.
EPC bands A–G
- The seven lettered groups the 1–100 score is divided into: A is 92–100 and G is 1–20. Bands make scores easier to read but homes within one band can still differ markedly.
F
Floor area
- The total useful floor area of the home recorded by the assessor, in square metres. It feeds the modelled assessment, and homes of very different sizes can receive similar scores because the methodology standardises for size.
I
Improvement measure
- A specific change identified by the assessment methodology for a property, such as insulation, heating controls or solar panels. Measures are recorded on the certificate in a set order.
M
Mean
- The arithmetic average of a group of scores. Published alongside the median so readers can see whether a few very high or low scores pull the average away from the middle.
Median
- The middle value when scores are ordered (or the average of the two middle values for an even-sized group). At least half the scores are at or below the median and at least half are at or above it. Tied scores mean the shares strictly above and below need not be equal.
O
Official EPC register
- The UK government service where domestic certificates for England, Wales and Northern Ireland are published and can be looked up by address; Scotland maintains its own register. EPC Benchmark is not connected to the register and cannot retrieve, confirm or amend a certificate — always treat the register as the authoritative source for a specific property.
OGL / Open Government Licence
- The licence under which official EPC register data and many other public datasets can be reused, with attribution. EPC Benchmark's analysis is built on data used under the Open Government Licence v3.0.
P
Postcode district
- The first part of a postcode, such as M11, SW1A or AL1. It is the finest geographic level this site uses: no street addresses or full postcodes are requested, stored or shown.
Potential gap
- The difference between a certificate's current score and its potential score. In this release it is a total, certificate-level figure: it is not the point uplift of any single measure.
Potential rating
- The score the assessment methodology predicts the home could reach if the recommended measures on that certificate were carried out. It is a modelled estimate, not a guarantee.
Property type
- The broad category recorded on the certificate — house, flat, maisonette or bungalow. It is one of the main attributes used to group genuinely similar homes in the published comparisons.
R
RdSAP
- Reduced data Standard Assessment Procedure: the simplified version of the SAP methodology used to assess existing (rather than newly built) homes, based on the characteristics an assessor can observe on site.
Recommendation
- An improvement measure the methodology identified for a property, listed on the certificate in a recorded order. Figures on this site count how often recommendations appear; they describe associations with the certificate's total potential gap, never item-specific causal uplifts.
S
SAP score / rating
- The 1–100 figure produced by the Standard Assessment Procedure, the UK methodology behind domestic EPCs. It models energy performance under standard occupancy assumptions, so it compares homes on a common basis rather than predicting any household's bills.
Suppression
- A privacy rule: any published group with fewer than 5 properties is withheld entirely, so no small group can be identified from the figures. Some views are therefore unavailable for smaller districts.
U
UPRN
- Unique Property Reference Number: a national identifier assigned to each addressable property. In the source analysis, valid UPRNs are used to reduce the certificate history to one current property per home. EPC Benchmark never displays UPRNs and does not ask for them.
Put the vocabulary to use
See the terms applied to real published figures, or read the detail behind how the aggregates are produced.