understanding epc calculations mark sreeves and lisa dores
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Understanding EPC Calculations
Mark Sreevesand
Lisa Dores
Who are National Energy Services?
• Established 1990
• Based in Milton Keynes
• Own and operate NHER and SAVA
• Co-developed RDSAP
• One of the first Accreditation Schemes for Domestic Energy Assessors
Presentation Overview
• Background• EPBD requirements for dwellings• SAP scale, 2001 and 2005• RDSAP development• Sensitivities
• Case Study• DEA process in example property• EPC Online• Relevant RDSAP conventions
RDSAP Methodology
• Energy Performance of Buildings Directive (EPBD) requirements
• Existing approaches & the need for a faster SAP
• Developing the dataset and methodology
EPBD January 2003
• Article 1, overall objective to reduce energy consumption
• Article 3, appropriate energy calculation methodology
• Article 7, energy performance certificates
• Article 10, ‘independent’ ‘experts’
• Article 15, transposition into law
EPBD Summary
• Energy Performance Certificate (EPC)
• Energy assessment methodology
• Independent energy experts
• Delivery legislation
RDSAP Methodology
• Energy Performance of Buildings Directive (EPBD) requirements
• Existing approaches & the need for a faster SAP
Standard Assessment Procedure
For any given dwelling :-
• An estimate of the energy costs for space heating, hot water and lighting
Utilising :-
• Standard occupancy criteria
• Standard weather conditions, geographical location and other geographical factors.
The SAP Scale
SAP 2001 - SAP 2005
0
20
40
60
80
100
120
140
160
-2 -1 0 1 2 3 4 5 6 7 8 9 10
ECF (£/m2/year)
SA
P
SAP 2001
SAP 2005
Why Not Use Full SAP ?
• Full SAP requires full dataset
• Large number of data items
• Some items only available through new build design process
• Inferences and assumptions required for existing dwellings
Using Existing SAP Methods
• Different systems in existence :-• NHER, Elmhurst & MVM systems• Other software providers• Stock profiling systems
• Directive requires “a common approach to this process”
Common Approach: Other Reasons
• Comparison: • “Consumers to compare and assess energy
performance of the building”
• Encouragement: • “Promote the improvement of the energy
performance of the building”
• User confidence: • Surveyors - don’t want complaints from customers• Government - legal requirement, don’t want
criticism
RDSAP Methodology
• Energy Performance of Buildings Directive (EPBD) requirements
• Existing approaches & the need for a faster SAP
• Developing the dataset and methodology
RDSAP Development
• NHER, Elmhurst & MVM were commissioned in 2002 :-• Phase 1 – Data set, inferences, approach• Phase 2 – Testing• Phase 3 – Revisions• Phase 4 – Energy Report• Phase 5 – Quality Assurance• Phase 6 – Field Trials
Initial Dataset
• Criteria• Accuracy• Repeatability• Length of survey/time
• Existing Methodologies• Elmhurst, MVM and NES systems differed in a
number of areas• Initial dataset contained the best features of
each• Dataset not influenced by commercial
constraints
Sensitivity Testing
• Full SAP data items examined for sensitivity
• Comparison between full SAP and initial dataset
• Initial dataset reassessed
• Inferred or actual data ?- Sensitivity plus surveyor accuracy
• Assumptions, inferences and surveyed items defined
Sensitivity Examples (1)
• Number of external doors :-• High data variation – little variation in result
• Number of doors can be assumed
• Based on dwelling type etc.
• Room Height :-• Potential large variations in SAP
• 2.4 m – 2.2 m = 2 SAP points
• Need to measure room height
• Relatively easy !
Sensitivity Examples (2)
• Window area :-• Potential large variations in area
• Time consuming to measure
• Potential surveyor errors
• Best approach to use set of equations based on age and built form
• 25% in window area = 1 SAP point
Non Standard Dwellings
• Non standard – accurate rating only requires extra data collection• Excess glazing, more than one extension
• Excluded – accurate rating cannot be provided due to limitations of the SAP model• HMOs, sheltered housing
Field Trials
• Dataset consolidation
• Repeatability
• Accuracy
• Time requirements
• Dataset finalised
Field Trials (1)
Field Trials (2)
Field Trials (3)
Field Trials - Conclusions
• Greater consistency achieved with simpler properties
• Larger/more complex properties showed greatest variation
• Definite identifiable need for clear conventions and good training
• Assisted in refining the RDSAP methodology
RDSAP Methodology
• Energy Performance of Buildings Directive (EPBD) requirements
• Existing approaches & the need for a faster SAP
• Developing the dataset and methodology
• Current status
EPC Assessment
• Must be undertaken by Domestic Energy Assessors (DEAs) or Home Inspectors (HIs)
• DEA qualification is a Level 3 Diploma, HI qualification is a Level 4 Diploma
• All must belong to Accreditation or Certification Scheme
• DEA/HIs will be able to work in rental sector – social housing etc.
• EPC Online
Case Study
EPC Online - General
EPC Online - Construction
Secondary Heating
EPC Online - Heating
Windows
EPC Online - Openings
Final EPC – Page 1
Final EPC – Page 2
Final EPC – Page 3
Final EPC – Page 4
Final EPC – Page 5
Final EPC – Page 6
Final EPC – Page 7
Current Status (England & Wales )
• 1 August 2007 EPCs required for the marketed sales of existing dwellings with >=4 bedrooms. For newbuild, Interim and Predicted Energy Assessments.
• 1 October 2007 EPCs required on construction of all new dwellings
• 6 April 2008 EPCs required for sale/rent of non-dwellings of over 500 sqm and EPCs required for the construction of all non-dwellings and 'Display EPCs' required for public buildings of over 1,000 sqm
• 1 October 2008 EPCs required for rental of all dwellings and all remaining sales. EPCs required for the construction, rental or sale of all other non-dwellings.
NHER Web Links and Contact Details
• www.nher.co.uk
• www.dea-training.co.uk