Independent building energy consultancy

The League Table & Rafts methodology

A systematic, evidence-based framework for ranking every possible energy-improvement measure and turning the ranked list into three costed, cumulative implementation pathways. Applied consistently across every DEAR and NDEAR report we lodge.

Authored by Zak Henning, Managing Director & Energy Assessor · Quidos accreditation QUID201039.

Two advice-report families

Same methodology, two lenses. Choose the report that matches the property and the purpose.

DEAR
Domestic Energy Advice Report

For: Residential landlords under domestic MEES

Model: RdSAP 10

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NDEAR
Non-Domestic Energy Advice Report

For: Commercial landlords under non-domestic MEES, and owner-occupiers with a specific operational or capital objective (cold rooms, carbon reduction, plant efficiency)

Model: SBEM (iSBEM), with heat-loss calculations where the brief requires

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1

Stage 1 — The League Table

We start by establishing a baseline energy model of the property in RdSAP 10 (domestic) or iSBEM (non-domestic). Every candidate improvement measure is then modelled separately, as a single change against the baseline. Measures are not stacked at this stage — because measure interactions in SBEM and RdSAP are non-linear, premature stacking hides which measure actually delivered which result.

Five scoring criteria

1
EPC Points Gained
SAP or SBEM asset-rating improvement — best measure ranks highest.
2
Energy Saving (kWh/m²/yr)
Absolute energy reduction against the baseline model.
3
CO₂ Reduction
Carbon saved (kg/m²/yr non-domestic; tonnes/yr domestic).
4
Cost Saving (£/yr)
Annual bill impact using current fuel prices.
5
Payback Period
Installed cost ÷ annual saving; 7-year test flag applied for non-domestic.

Why BER, not TER? For non-domestic advice we use BER (Building Emission Rate) as the carbon comparison basis — it reflects the actual as-modelled building performance independent of the notional target. TER only shows headroom against a moving compliance target; BER shows real measure impact.

2

Stage 2 — The Rafts

Once the League Table is complete we group the highest-ranked measures into three cumulative implementation stages, called Rafts. Each Raft is then re-modelled as a stacked scenario — you cannot simply add up the isolated measure results because their interactions are non-linear. Every Raft output is a genuine combined SBEM or RdSAP run.

1

RAFT 1 — Priority Measures

Target: Immediate compliance + heating and fabric basics

Most impactful, most cost-effective measures. Where a regulatory minimum applies (Band E now; proposed EPC B by 2031 for non-domestic buildings over 1,000 m², and domestic Band C from 1 October 2030) Raft 1 achieves it. Domestic: E compliance / quick wins. Non-domestic: E with 7-year payback compliance.

2

RAFT 2 — Secondary Improvements

Target: Band C mid-term target

Cumulative with Raft 1. Fabric upgrades and controls added. Domestic: EPC C for 2030. Non-domestic: interim Band C milestone.

3

RAFT 3 — Deep Retrofit

Target: Band A or B long-term pathway

Cumulative with Rafts 1 and 2. Adds generation (ASHP, PV, DHW electrification). Domestic: near-Band A. Non-domestic: Band B or A.

Each Raft report includes
  • Measures included
  • Total capital cost estimate
  • Combined annual energy cost saving
  • Resulting EPC band and rating
  • Resulting CO₂ emissions and energy consumption
Arithmetic addition is not valid

SBEM and RdSAP measure interactions are non-linear. Simply summing individual League Table results overstates or understates real outcomes. Every Raft is a full re-run of the model with all cumulative measures applied together.

Regulatory context we work to

Domestic MEES

  • Current minimum: EPC Band E (until Oct 2030)
  • Confirmed: Band C from 1 October 2030 for all tenancies
  • Cost cap: £10,000 per property (or 10% of value under £100k)
  • Registered exemptions available (cost cap, third-party consent, devaluation, etc.)

Non-Domestic MEES

  • Current minimum: EPC Band E (since 1 April 2023, all lettings)
  • 7-year payback test — statutory exemption route
  • Proposed EPC B by 2031 — buildings over 1,000 m² only, pending secondary legislation (DESNZ June 2026 interim response). 2027 EPC C milestone dropped.
  • Penalties calculated on rateable value & breach duration (Reg 39, EEPRPR 2015)

Known limitations — declared upfront

Independent consultancy means telling you what the models can and cannot do. Every advice report we issue carries a plain-English statement of these limitations so decisions are made with the full context.

RdSAP / SAP

  • Standard occupancy assumptions — does not reflect individual household behaviour.
  • Heating controls captured for efficiency, not operational-hour savings.
  • Does not model time-of-use tariffs (HHRSH partly tariff-driven).

iSBEM / SBEM

  • Lighting energy can show modelled BER worsening despite real-world cost savings.
  • Air permeability defaults to 15 or 25 m³/(h·m²) if not measured on-site.
  • Auxiliary loads (pumps, fans) not fully dynamic; controls optimisation not fully captured.

Cost & Fuel Prices

  • Indicative costs from published 2024–2026 market benchmarks; client-provided quotes replace estimates.
  • Fuel prices 2026: gas 7.5–8.0 p/kWh; electricity 23–25 p/kWh.
  • Long-term price forecasts inherently uncertain.

Quality assurance

Six checks applied to every advice report before it leaves us.

  • 1
    Baseline model verified against survey and site notes.
  • 2
    Each measure confirmed as isolated change from baseline — no measure stacking at League Table stage.
  • 3
    Metric extraction cross-checked against model export reports.
  • 4
    League Table reviewed for anomalies (SBEM lighting-worsening, negative CO₂ etc.).
  • 5
    Raft cumulation verified by comparing isolated vs cumulative runs — no arithmetic addition.
  • 6
    Every figure in every report traced back to a model run or a documented calculation.

Accreditation: Domestic and non-domestic energy assessments lodged under Quidos accreditation QUID201039. The League Table + Rafts methodology is a proprietary Energy Performance Direct process, publicly documented here for transparency.

Methodology questions

Why do you use BER rather than TER for non-domestic carbon comparison?
BER (Building Emission Rate) reflects actual as-modelled performance independent of the notional target building. TER (Target Emission Rate) only shows compliance headroom against a moving target. For advice work — where we are comparing measure impact — BER gives a cleaner apples-to-apples view.
Why isolate each measure rather than stacking them?
Because measure interactions in SBEM and RdSAP are non-linear. Stacking prematurely obscures which measure actually delivered the improvement. Isolation lets us rank fairly across five criteria, then re-stack cumulatively as Rafts for real-world implementation planning.
Why five scoring criteria and not one?
A one-number score always privileges one dimension (usually carbon or cost) and hides trade-offs. Landlords care about £/yr; regulators care about EPC band; carbon reporting cares about kgCO₂/m²/yr; investors care about payback. Ranking across all five surfaces the measure that wins on the criterion the client cares about most.
What is the 7-year payback test?
Under the Minimum Energy Efficiency Standards for non-domestic property (Energy Efficiency (Private Rented Property) (England and Wales) Regulations 2015, Regulation 28(3)–(8)) the 7-year payback test operates as a statutory exemption: where the cost of a recommended improvement measure — or package of measures — is greater than the expected value of energy-bill savings over 7 years from installation, the landlord may register a 7-year payback exemption on the PRS Exemptions Register in place of installing that measure. The government confirmed in its June 2026 interim response that the 7-year payback test remains. Our League Table flags every non-domestic measure against this test so landlords can distinguish measures they are compelled to install from those that fall outside the statutory obligation.
How does DEAR differ from NDEAR?
DEAR uses RdSAP 10 for residential dwellings; NDEAR uses iSBEM for non-domestic (commercial) properties. Both apply the League Table + Rafts methodology, but the metrics differ: DEAR ranks by SAP points, kWh/m²/yr, tonnes CO₂/yr, £/yr and payback. NDEAR ranks by SBEM asset rating, BER, total energy, £/yr and payback with the 7-year test flag. NDEAR also covers non-MEES engagements — for example, owner-occupiers looking at cold rooms, carbon reporting or plant-replacement decisions — with complementary heat-loss calculations added where the brief requires.
Are Raft cost estimates guaranteed?
No. Costs are indicative benchmarks from 2024–2026 market data. Every Raft report tells you to obtain three contractor quotes before committing. Where a client provides real quotes, we replace the indicative figures and re-run the Raft calculation.
Is this methodology accredited or externally reviewed?
Our energy assessments are lodged under Quidos accreditation (QUID201039). The League Table + Rafts methodology itself is a proprietary Energy Performance Direct process — publicly documented on this page for transparency, and applied consistently across every DEAR and NDEAR report we lodge.
How is this methodology different from a standard EPC recommendations report?
A standard EPC recommendation list gives a fixed set of measures with no ranking, no interaction modelling, and no capital cost figures. Our League Table + Rafts approach ranks every measure across five criteria, tests them individually then cumulatively, and reports three costed implementation pathways with modelled band outcomes. It's an independent consultancy output, not a compliance form. See a full worked example in the Exeter G-to-A office case study.

Commission a DEAR or NDEAR advice report

Baseline + three costed Raft pathways + full League Table working file. Tell us the property and the purpose and we'll scope the report.

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