One of the most common questions we receive at Sefaira is this:
"Can I use Sefaira calculations to comply with my local energy code / green building certification?"
This article answers this question generally. Where we are able to provide specific information we'll add links below.
Article in Summary
- Sefaira's calculations are generated using an engine that meets all the building physics criteria for all known energy codes. To this end, we are confident that the calculation basis is equivalent to the expectations of energy codes and standards if those standards are based on dynamic annual simulation.
- Sefaira's interface is limited (deliberately) and does not currently contain all the controls that would be expected for most buildings as part of a complete energy code submission.
- Overall we believe Sefaira is capable of providing a fair and reasonable estimate of likely energy code performance given inputs likely to be known at Schematic Design (RIBA stage 2).
- Sefaira is unlikely to be suitable for compiling a final code compliance documentation submittal at a later stage. Other software or native use of EnergyPlus will be required.
Our primary goal is to provide performance guidance at early stage design that is as accurate as inputs allow via easy to use and learn workflows. This includes guidance on whether designs are "on track" to comply with an energy code or standard.
What we mean by Energy Code?
In answering this question we generally mean things codes and standards that require or encourage energy analysis of a whole building model to demonstrate compliance. Examples include:
- ASHRAE 90.1 (and therefore LEED)
- CIBSE Part L (and therefore BREEAM)
- Section J from Building Code of Australia
There are many others.
Typical analysis requirements of energy codes
Most of the energy codes are looking for submissions to use software that meets a certain standard or set of guidelines. Typically these requirements are looking for things like:
- Hourly simulation using dynamic weather data
- Ability to reasonably define the geometry and materials of the building
- Ability to satisfactorily define the HVAC system of a baseline and proposed building
- Ability to create thermal zones within the building
- Ability to provide diversity schedules to different internal loads
Sometimes they will also seek certification such as BesTest certification. These tests check whether the space load calculations carried out by the software on a fairly simple building form fall within an acceptable tolerance range. They do not validate HVAC configuration or energy use from an HVAC system, just space loads.
Status of EnergyPlus for meeting requirements
EnergyPlus keeps track of their compliance with testing standards and reports it here:
In some cases it is the only engine considered acceptable for compliance.
It has passed certification for heat load transfer and is often the benchmark standards have been developed from.
Areas where Sefaira complies because we run on EnergyPlus
Sefaira runs all energy calculations on EnergyPlus. Sefaira space load calculations which form the basis of energy analysis all come from EnergyPlus. Therefore the heat balance equations and checks that are carried out by certification tools like BesTest should automatically be considered to comply with Sefaira.
Overall the Precision of the calculations based on the inputs provided should be as good as any other software.
In addition Sefaira provides reporting in EnergyPlus native format so that the raw data generated by the base energy analysis tool can be seen.
Areas where Sefaira is limited in its capacity to comply - Interface
Sefaira's interface is constrained to make it faster and easier to use. While we are constantly looking to add new features and improve the interface, the limited level of control often means that we are not able to provide all the inputs expected of energy codes and standards.
Current areas which limit Sefaira being directly used for some codes include:
- Space Use Schedules and the ability to divide them up between different use types
- The ability to apply multiple HVAC systems to a single energy model (there is a group feature to form iterations made up of multiple systems but they are separate energy models)
- Some HVAC controls
- Some geometry interpretation
- Domestic Hot Water calculations (although these can often be done separately)
We are actively looking at how to improve our product to address these issues. All of these constraints can be overcome using EnergyPlus natively.
Areas where Sefaira is limited in its capacity to comply - Certification
Some codes and standards have very onerous certification compliance pathways. This is particularly true of CIBSE Part L compliance, especially if a simulation model is to be used. Sefaira has not sought certification via these standards as yet.
Known status of Sefaira's compliance state
Codes and Standards where we believe Sefaira complies today
- ASHRAE 290
- LEED v4 Early Stage Energy Analysis
- BREEAM Early Stage Energy Analysis
Codes and Standards where we are limited by interface issues only
- ASHRAE 90.1
- LEED Energy Credits
- BCA JV3
Codes and Standards where we are limited by interface and certification issues
- CIBSE Part L
- SAP calculations