Green building certification comparison: DGNB, LEED, BREEAM and ASHRAE
Most sustainable building certification comparisons stop at credit categories. This one looks at the part that drives engineering hours: the building performance simulations each framework expects, and how the resulting documentation differs. Written from CHAAC's experience delivering simulation packages for consultants internationally.
Side-by-side comparison
| DGNB | LEED | BREEAM | ASHRAE | |
|---|---|---|---|---|
| Origin & governing body | DGNB (Germany), from 2008 | USGBC (United States), from 1998 | BRE (United Kingdom), from 1990 | ASHRAE (United States) — standards, not a certification label in itself |
| Scoring logic | Weighted performance index across quality sections, expressed as a percentage | Point-based credits with prerequisites, four award levels | Weighted credits by category, rated Pass to Outstanding | Compliance against a baseline or prescriptive path, pass / fail in nature |
| Energy modeling | Dynamic building simulation commonly used to evaluate energy demand and life-cycle related criteria | Whole-building energy simulation compared to an ASHRAE 90.1 Appendix G baseline for the energy performance credit | Energy modeling used for the energy performance assessment, with national scheme variations | 90.1 Appendix G defines the baseline methodology many schemes reference |
| Thermal comfort | Dedicated thermal comfort criterion evaluated with dynamic simulation over summer and winter conditions | Comfort credit referencing ASHRAE 55; often supported by simulation on complex projects | Thermal comfort assessment supported by dynamic thermal modeling | Standard 55 defines the comfort criteria themselves |
| Daylight | Daylight criterion typically documented with daylight factor studies | Daylight credit assessed with sDA and ASE, or measurement | Daylight credits assessed with daylight factor or illuminance criteria | Not covered by the energy standards |
| Typical simulation tools | IESVE and comparable dynamic simulation engines; Radiance for daylight | IESVE, EnergyPlus-based tools, Radiance-based daylight engines | IESVE and comparable dynamic engines, per scheme guidance | Any modeling tool meeting the standard's capability requirements |
| Documentation burden | Extensive structured documentation per criterion | Credit-by-credit forms and supporting model outputs | Evidence-based, assessor-reviewed submissions | Baseline versus proposed model reports. For permit compliance and financial incentives |
Scheme requirements change between versions and national adaptations — always confirm against the current manual for your scheme version and region. References: DGNB, USGBC LEED, BREEAM, ASHRAE 90.1.
What this means for the simulation scope
Whichever label a project pursues, three analyses carry most of the technical weight: whole-building energy simulation, dynamic thermal comfort, and daylight. The physics does not change between schemes — the baselines, reporting formats and evidence expectations do.
The practical consequence is that reuse happens at the model level, not at the deliverable level. A single well-structured dynamic model can feed several frameworks, but each one needs its own baseline definition, its own assumption record and its own report structure. Underestimating that documentation layer is the most common source of schedule pressure late in a certification process.
That is exactly why we publish report and calculation templates: they standardise the documentation side so the engineering time goes into the analysis.
Frequently asked questions
- What is the main difference between DGNB, LEED and BREEAM?
- DGNB scores a weighted performance index across quality sections including life-cycle considerations, LEED awards points against defined credits and prerequisites, and BREEAM uses weighted credits reviewed by a licensed assessor. In practice they overlap heavily in the physics they ask you to demonstrate — energy, thermal comfort and daylight — but differ in how evidence is structured and reviewed.
- Where does ASHRAE fit in?
- ASHRAE publishes standards rather than a certification label. Standard 90.1 Appendix G is the baseline methodology referenced by LEED and by many permit-compliance routes, and Standard 55 defines thermal comfort criteria used across several schemes.
- Can one energy model serve several certifications?
- A well-built dynamic model can usually be reused as a technical basis, but each scheme requires its own baseline definitions, reporting formats and assumptions documentation. Expect additional runs and separate deliverables rather than a single submission that satisfies everything.
- Which simulations are needed most often?
- Across DGNB, LEED and BREEAM the recurring deliverables are whole-building energy simulation, dynamic thermal comfort analysis and daylight analysis. Solar exposure studies appear on projects with significant glazing or shading complexity.
Documentation templates for these frameworks
Free thermal comfort, daylight factor and solar exposure templates — structured documentation used on real building performance deliverables.