Trial / Demo
On 22 July 2026, we hosted a webinar on ASHRAE 90.1 Compliance with IESVE. Attendees asked questions spanning PRM workflows, baseline model generation, HVAC system modelling, LEED requirements, and general use of the IESVE Navigator.
We've compiled the most common questions below as a reference for webinar attendees and anyone looking to streamline their ASHRAE 90.1 compliance workflow in IESVE.
The IESVE Navigator is a workflow management tool that guides users through complex building performance analysis and compliance processes. It provides a structured, step-by-step workflow covering model setup, simulation, compliance checking, and reporting.
Why are there multiple options such as “Select ASHRAE Standard” and “ASHRAE Prototype”?
These options support different project requirements:
Both options are integrated into the Navigator to streamline the modelling and compliance process, reduce errors, and save time
Navigator workflows are configured around specific compliance requirements, templates, and datasets. Once assigned, changing the workflow could invalidate previously generated compliance data and calculations.
No. You must create the proposed case model first and then generate the baseline model from it.
No. The proposed model must be completed before generating the baseline model.
Yes, the IESVE Navigator for ASHRAE 90.1 provides a highly automated workflow for baseline model generation, including the HVAC system. After automatic generation, users can review and, if needed, manually adjust any special baseline geometry or system features to address project-specific requirements.
The IESVE Navigator significantly reduces manual effort by automating the creation and assignment of baseline HVAC systems and other compliance elements, ensuring faster and more accurate ASHRAE 90.1 modelling workflows
Users can review and adjust special geometry or system features afterward if required.
Yes. The Navigator automatically adjusts baseline glazing to comply with ASHRAE 90.1 requirements.
If the proposed building exceeds the allowable WWR limit (typically 40%), the software automatically reduces glazing while maintaining the façade distribution proportions specified by Appendix G.
Yes. The Navigator automatically calculates baseline ventilation requirements for multiple-zone systems in accordance with ASHRAE 62.1 Normative Appendix A.
Most of them are.
Automatically generated items include:
However, users should still review and manually adjust project-specific elements where necessary.
Yes.
Yes.
If you need to set up a baseline model in IESVE based on your local guidelines (rather than ASHRAE 90.1), you can do so by following a custom workflow.
IESVE offers dedicated Navigators for various international and local codes, such as UK Part L, NECB (Canada), and others. If your local code is supported, select the relevant Navigator at the start of your project.
If your local guideline is not directly supported, use the generic workflow and manually configure the baseline model.
IESVE’s simulation environment is designed to support this process, enabling you to model, test, and optimise building systems, including HVAC, for both new and existing buildings.
The platform is used to inform decision-making, reduce operational costs, and support decarbonisation strategies. By comparing the baseline to actual or target performance, you can pinpoint “weak spots” in the building’s operation or design - such as underperforming HVAC systems, poor insulation, or inefficient controls. Detailed simulation provides an accurate breakdown of energy use by system and equipment, enabling you to evaluate the performance of HVAC components under different conditions and identify where upgrades or tuning could yield the most benefit.
No. DHW modelling is not fully automated.
Users must:
No.
The baseline system should remain as defined by ASHRAE 90.1 Appendix G requirements.
For example:
Yes.
The fresh air requirement in IESVE is typically determined as a function of occupancy, most commonly set at 8 litres/second per person (8 l/s/person), in line with UK and international standards. This value can be adjusted to meet local codes or project-specific requirements.
The software multiplies the occupancy of each room by the required fresh air rate per person to determine the total fresh air volume needed. The fresh air requirement set at the room level is used to size the supply airflows for terminal units and air handling units (AHUs) in the HVAC system.
In ApacheHVAC, the Room Ventilation & Exhaust tab contains the fresh air requirements, which drive the controllers for supply and exhaust airflows.
The standard simulation report in IESVE typically shows only the total unmet load hours for the building or system, not a breakdown by individual room. However, you can identify which rooms are responsible for unmet load hours by using the Vista Results (VistaPro) for Detailed Analysis by selecting air temperature variable and range test tool
Follow the PRM Navigator workflow:
The Navigator then uses the generated load data to size baseline systems according to ASHRAE 90.1 Appendix G requirements.
The standard simulation report only reports total unmet load hours.
To identify problematic rooms:
This allows you to isolate rooms experiencing temperature issues and unmet loads.
ASHRAE 90.1 serves as an internationally recognised benchmark and is frequently referenced by:
Many local codes also reference or incorporate ASHRAE requirements.
The appropriate approach depends on the authority having jurisdiction and project requirements. The applicable compliance route should be reviewed and coordinated with project stakeholders.
PRM is the ASHRAE Appendix G methodology that compares:
The energy cost or energy performance difference determines compliance and rating outcomes.
Appendix G defines the Performance Rating Method and specifies:
Appendix D is not used by the IESVE ASHRAE 90.1 Navigator workflows and is not part of compliance pathways such as Appendix G or Section 11.
The appendix is simply a placeholder and does not impact your modelling, reporting, or compliance submissions
Yes.
ASHRAE 90.1 applies to:
No.
IESVE compliance workflows are based on ASHRAE 62.1, which is the applicable standard for high-rise residential buildings and commercial projects.
Availability depends on software updates and releases. Users should check the latest IESVE release notes for supported standards.
Yes, with limitations.
IESVE can model:
However, cooling tower cycle calculations and water quality assessments required for the credit generally require external calculations (often in Excel).
Submit:
The Energy and Atmosphere category offers up to 33 points.
Energy modelling is central to demonstrating compliance and earning these points.
Export it from:
Tool bar in Vista pro → Content Manager → Export
An MEPC sheet is a summary document that consolidates project information for:
It is often used as supporting documentation for compliance submissions.
The total floor area should only include occupied floor plates.
Roof areas are generally not considered part of the building floor area for compliance calculations and reporting.
The Space-by-Space Method assigns:
to each room individually according to its specific function.
This provides more detailed and accurate modelling than broad building-level assignments.
Recommended workflow:
Baseline modelling helps users:
This workflow requires the IESVE Expert Pack license.
Yes.
IESVE includes:
Yes.
IES provides an On-Demand Learning Platform with tutorial videos covering:
Take a look at all available IES Training options.
IESVE also supports HVAC design, energy modelling, decarbonisation studies, daylighting analysis, and operational performance optimisation, and automates much of the baseline model creation and compliance reporting covered above.
To learn more:
Contact our sales team to arrange a demo or discuss your requirements.
