Just need the figures? The building regulations reference has the Part L U-values and dates, Part O tables, Part G factors, Part E limits, SAP carbon factors and the regs calendar on one page, dated and sourced.
- Asked for a water efficiency certificate? Here is what actually exists
What a Part G water efficiency certificate really is, what the document must show, and how to produce one free.
- 125 litres per person per day, explained
How the 125 l/p/d water calculation works, and which standard applies to your site.
- The 110 litres per person per day planning condition
The tighter optional water standard many councils require, and how to meet it.
- What is Thermal Bridging?
Why junctions leak heat, what Ψ-values are, and how calculated values improve your SAP result.
- New build compliance: what you need at each stage
Planning to completion certificate in order: every energy, water, overheating and testing requirement for a new home, and when each one is due.
- What is a psi value?
The Ψ-value in plain English: units, typical values per junction, SAP's default and notional figures, and how one is calculated.
- Why two U-value calculators give different answers for the same wall
The five real causes of a differing U-value, and how to check which calculator is right.
- Building Regulations Part L Explained
What Part L requires for new dwellings, extensions and conversions — which edition applies, and what changes in 2027.
- Part L photographic evidence: what to photograph, and when
The 13 details every new dwelling needs photographing under Part L 2021, when to catch each one on site, and a free printable plot checklist.
- Building Regulations Part O explained
What Part O requires of new homes: the simplified method's glazing and free-area limits, when TM59 modelling is needed, and the noise rule that decides it.
- What is PHPP (and when do you actually need it)?
What PHPP is, which planning policies require it for an energy statement, and how it differs from Passivhaus certification.
- SAP 10: What's New in Part L 2021?
The SAP 10 changes that matter: tighter notional dwelling, PV assumption, new carbon factors, thermal bridging.
- What is the Future Homes Standard?
The 2027 standard for new homes in full: mandatory solar PV, tighter U-values, heat pumps, SAP 10.3 vs HEM, costs and transitional dates.
- What is DER/TER?
The dwelling vs target CO₂ emission rates at the heart of every SAP pass or fail.
- What is Fabric Energy Efficiency (DFEE/TFEE)?
The kWh/m²/yr fabric target that ensures the building itself — not just its renewables — performs.
- What is a U-value?
The W/m²K measure of element heat loss, how it is calculated, and the Part L limits that apply to new builds, extensions and renovations.
- Accredited Construction Details (ACDs) and Recognised Construction Details (RCDs) explained
ACDs (retired), RCDs (current, masonry) and calculated psi values — what each is and which to use under SAP 10.
- What is the Energy Hierarchy?
The reduce-first principle behind Part L and most planning energy policies.
- Why is Fuel Choice Important in SAP?
How gas, electric, heat pump, LPG and oil choices change a SAP result.
- What is a Predicted Energy Assessment (PEA)?
The off-plan predecessor to the EPC, produced from design-stage SAP.
- Building regulations for an extension: the energy side, start to finish
The 25% opening allowance, the covered-openings credit, the Table 4.2 U-values every new element must meet, and the three routes when the glazing goes over.
- Building regulations when you renovate: the upgrades you may not expect
The 50% renovation trigger, the Table 4.3 thresholds and improved values, the 15-year payback escape, and how replacements, conversions and controlled fittings differ.
- Renewable Technologies: An Overview
The main low-carbon technologies compared, with their SAP impact.
- Solar PV (Photovoltaic Panels)
Electricity-generating panels: the workhorse of SAP passes and planning conditions.
- Heat Pumps: An Introduction
How heat pumps work and why they're the new-build heating default.
- ASHP — air source heat pumps explained
What ASHP means, how it works, real efficiency, grants, planning and noise rules, and how it scores in SAP.
- Ground Source Heat Pumps (GSHP)
The high-efficiency, high-cost heat pump: loops, boreholes and SAP performance.
- Solar Hot Water (Solar Thermal)
Solar thermal for hot water — and when PV + diverter beats it.
- MVHR (Mechanical Ventilation with Heat Recovery)
Whole-house ventilation that recovers heat — ideal for airtight new builds.
- WWHR (Waste Water Heat Recovery)
Shower drain heat recovery: small cost, easy SAP points, assumed in SAP 10's target.
- FGHR (Flue Gas Heat Recovery)
Recovering flue heat from gas boilers for extra hot-water efficiency.
- What is Weather Compensation?
Outdoor-sensing heating control that lowers flow temperatures and earns SAP credit.