Sustainability
Sustainability and net zero design
Part L and Section 6 compliance, energy modelling, heat decarbonisation and Passivhaus design for buildings across the UK.
- Discipline
- Sustainability
WHAT IT IS
Sustainability in building services is mostly a set of ordinary engineering decisions made well: load calculated properly rather than padded, systems selected on lifetime performance rather than capital cost, plant sized to demand, and controls that actually deliver the design intent.
SDE covers the compliance route — Part L in England and Wales, Section 6 in Scotland — and the work beyond it: options appraisal, heat decarbonisation, overheating assessment and Passivhaus design where the client is pursuing certification.
SERVICES
Services in this discipline
BREEAM MEP design and credit support
Building services design and evidence for the BREEAM credits the MEP engineer controls — energy, water, health and wellbeing, and pollution.
Dynamic thermal modelling and overheating assessment
Dynamic simulation for overheating risk, comfort and energy — TM52, TM59, Approved Document O and TM54 — run while the facade can still change.
Heat pump and low carbon heat design
Heat pump design for new build and retrofit — flow temperature and emitter sizing, hot water and legionella control, electrical capacity and acoustics.
Net zero and energy strategy
Energy strategy for planning and for real performance — the hierarchy, the options appraisal, and the gap between the compliance model and the meter.
Non-domestic EPCs and energy assessment
Level 3, 4 and 5 non-domestic EPCs, lodged by an accredited assessor, with the recommendation report and the Scottish Section 63 action plan where it applies.
Part L compliance modelling, England and Wales
Non-domestic Part L compliance modelling and BRUKL reporting at design and as-built stage, run early enough to change the design rather than to report on it.
Passivhaus building services design
Building services design for Passivhaus certification, including PHPP input, ventilation strategy and the low-load plant selection it requires.
Section 6 energy compliance, Scotland
SBEM and dynamic simulation modelling for Section 6 compliance in Scotland, produced as part of the building warrant application rather than after it.
TM65 embodied carbon assessment
Embodied carbon of MEP systems to CIBSE TM65, for whole life carbon assessments and for choosing between plant on more than capital cost.
WHEN YOU NEED IT
On every project, because Part L and Section 6 compliance is not optional. Earlier than most people expect if the target is anything beyond compliance — a net zero or Passivhaus target set at Stage 3 is a different and more expensive project than the same target set at Stage 1.
OUR PROCESS
Compliance modelling is run as a design tool during Stages 2 and 3, not as a submission exercise at Stage 4. A model that first runs after the design is fixed can only report the answer; a model that runs while options are open can change it.
Where a client is pursuing a target beyond compliance, the gap between the compliance model and the real energy prediction is stated explicitly. Notional-building compliance modelling is not an energy prediction and should never be presented as one.
DELIVERABLES
What you receive
- Part L or Section 6 compliance modelling
- Energy strategy report
- Options appraisal with capital, running cost and carbon
- Overheating assessment to TM52 or TM59
- Heat decarbonisation strategy
- Embodied carbon assessment of services to TM65
STANDARDS
Standards applied
The editions in force at the time of design. Where a standard is amended mid-project we confirm which edition the appointment is based on.
- Approved Document LConservation of fuel and power (England)GOV.UK
- Technical Handbook Section 6Energy (Scotland)Scottish Government
- Technical Handbook Section 7Sustainability (Scotland)Scottish Government
- CIBSE TM54Evaluating operational energy use at the design stageCIBSE
- CIBSE TM52Avoiding overheating in European buildingsCIBSE
- CIBSE TM59Design methodology for the assessment of overheating risk in homesCIBSE
- CIBSE TM65Embodied carbon in building servicesCIBSE
- PHPPPassivhaus Planning Package — Passivhaus InstitutPassivhaus Institut
QUESTIONS
Common questions
What is the difference between Part L and Section 6?
Part L is the energy section of the Approved Documents supporting the Building Regulations in England, with a separate Welsh version. Section 6 is the equivalent in the Scottish Technical Handbooks supporting the Building (Scotland) Regulations. They set different targets and use different compliance software, and a design compliant in one jurisdiction is not automatically compliant in the other.
Does compliance modelling predict a building’s energy use?
No. Part L and Section 6 modelling compares the building against a notional equivalent using standardised occupancy and operating assumptions. It demonstrates compliance but it is not a prediction of actual consumption. CIBSE TM54 sets out the separate methodology for predicting operational energy use at design stage.
When should overheating be assessed?
At concept stage, while glazing area, orientation, shading and ventilation strategy can all still change. CIBSE TM52 covers free-running non-domestic buildings — those not mechanically cooled — using adaptive comfort criteria; mechanically cooled buildings are assessed against a fixed comfort criterion instead. TM59 covers homes. Assessing overheating after the facade is fixed usually leaves mechanical cooling as the only remaining answer.