ORCalc
ORCalc is the name of the UK government-mandated software which is used to generate Display Energy Certificate (DEC) and Advisory Reports for buildings in the UK. ORCalc stands for Operational Rating (OR) calculation because it is based on a buildings actual operation energy consumption data.
This is as opposed to for example Energy Performance Certificates (EPCs) which look very similar but are generated using modelled building energy based either the Standard Assessment Procedure (SAP) methodology or Simplified Building Energy Model (SBEM) and a variety of assumptions.
It can be downloaded for free but is primarily used by energy assessors who are qualified and competent in the use of the software to produce DECs.
For further information visit: Guidance Display Energy Certificates and advisory reports for public buildings
aswell as https://www.uk-ncm.org.uk/index.jsp or https://www.ncm-pcdb.org.uk/sap/page.jsp?id=7
[edit] Related articles on Designing Buildings
- Accredited energy assessor.
- Air tightness.
- Are Energy Performance Certificates accurate?
- BS EN 15232 Energy performance of buildings: impact of building automation, controls and building management.
- Building performance.
- Building performance metrics.
- Carbon ratings for buildings.
- Certificates in the construction industry.
- CRC Energy Efficiency Scheme.
- Display energy certificate.
- Emission rates.
- Energy certificates for buildings.
- Energy efficiency of traditional buildings.
- Energy performance certificate EPC.
- Energy Performance of Buildings Directive.
- Energy related products regulations.
- Energy Savings Opportunity Scheme.
- Energy targets.
- Green mortgage.
- Home information pack HIP.
- Homebuyer Report.
- How are EPCs produced?
- How much does it cost to sell my home.
- Listed buildings.
- Minimum energy efficiency standard (MEES).
- Minimum energy efficiency standard regulations for domestic and non-domestic buildings.
- NABERS UK.
- National Calculation Method.
- National Retrofit Strategy NRS.
- Non-domestic private rented property minimum standard.
- Passivhaus vs SAP.
- Performance gap.
- Private rented sector regulations and traditional buildings.
- Retrofit.
- Simplified Building Energy Model.
- The EPC consultation in the context of changes to the NCM.
- The Home Energy Model and Future Homes Standard assessment wrapper.
- U-value conventions in practice: Worked examples using BR 443.
- Energy performance certificate EPC.
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Gasholders: a history in pictures. Book review.
Recognition, influence and growth
SocEnv identifies three strategic pillars in new strategy to 2045.
Discover the future of roofing, cladding and insulation.
New guidance for professional practice, cultural change and regulation in social housing.
The heritage of nuclear and conventional power stations.
New measures to stop people being ripped off
Government to protect families from cowboy builders and aggressive bailiffs.
New Futurebuild showcase brings an innovation-first approach.
National Planning Policy Framework
Understanding the 2026 changes.
ECA's public affairs priorities
Member consultation opens to shape priorities for 2027 to 2030.
Dutyholder responsibilities from 1 July 2026.
Where performance meets practice
The Building Envelope Stage at UKCW Birmingham.
CIAT publishes briefing on planning reforms.