IES Software Validation

Approved software solutions for international standards, methodologies, regulations and rating systems

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IES tools meet the following approved international standards.

ASHRAE 140: 2001, 2004, 2007, 2014, 2017



EU EN13791: July 2000


ISO 52000


IESVE meets or exceeds all of the requirements of the ANSI/ASHRAE/ACCA Standard 183 which sets minimum requirements for methods and procedures used to perform peak cooling and heating load calculations for buildings except low-rise residential buildings.

IESVE uses the Heat Balance (HB) Method to calculate cooling and heating loads of rooms, zones or buildings, in order to comply with the Standard. The ASHRAE Heat Balance Method is detailed in Chapter 18 of the ASHRAE Handbook – Fundamentals as the preferred accurate method for load calculations. Standard 183 specifies calculation methods and requirements for: 

  • Section 5 - Weather Data and Indoor Design Conditions; including hourly solar radiation per all building room surfaces.
  • Section 6 - Cooling Load Method; including hourly convective & radiative heat gains and effects of thermal mass on the cooling load. 
  • Section 7 - External Heat Gains; including sensible & latent heat gains from infiltration, opaque building envelope components with thermal mass effects, and solar gain through fenestrations with/without accounting for effects of blinds, shades or drapes. 
  • Section 8 - Internal Heat Gains; including hourly sensible & latent heat gains, number of occupants & activity levels, diversity load factors and (recessed) lighting heat gain to a ceiling plenum. 
  • Section 9 - Heating Load; including infiltration, cold processes (e.g. refrigerated cases) and the optional inclusion from internal heat gains. 
  • Section 10 - System Cooling and Heating Loads; including duct leakage, fan & pump energy, heat transfer through pipes & ducts, diversity of occupants/equipment/lighting and pyschrometric processes for reheat, dehumidification, humidification, air-mixing & airside heat-recovery (e.g. ERV).  
ISO 52000

IESVE meets or exceeds the requirements of the ISO 52000 series of standards, and the locally adopted standards version such as the German DIN EN 12831 or United Kingdom BS EN 12831.

ISO 52000 series of standards contains a comprehensive method of assessing energy performance as the total primary energy used for heating, cooling, lighting, ventilation and domestic hot water of buildings. The standards specify calculation methods for the assessment of: 

  • the (sensible) energy need for heating and cooling, based on hourly or monthly calculations
  • the latent energy need for (de-)humidification, based on hourly or monthly calculations
  • the internal temperature, based on hourly calculations
  • the sensible heating and cooling load, based on hourly calculations
  • the moisture and latent heat load for (de-)humidification, based on hourly calculations
  • the design sensible heating or cooling load and design latent heat load using an hourly calculation interval
  • the conditions of the supply air to provide the necessary humidification and dehumidification


IES tools can undertake the following methodologies.

ASHRAE 90.1 Performance Rating Method (PRM): 2004/07/10/13/16/19

ASHRAE 90.1 Energy Cost Budget Method (ECB): 2010/13/16

ASHRAE 55 Calculation Procedure

ASHRAE 62.1 Calculation Procedure

CIBSE Guide A/ISO 7730 Calculation procedure

UK National Calculation Methodology (NCM)

Model Validation Experiment Demonstrates Accuracy of IESVE

IES were asked through the University of Strathclyde to take part in an Empirical Whole Model Validation Twin House Experiment for the IEA-ECB Programme’s Annex 71 project. This particular experiment was a validation exercise for simulation tools, helping to demonstrate that they are capable of accurate predictions that can be verified against real world measurements.

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Approved Solar Ready Software

The VE is officially approved by the CEC as a Solar Assessment Tool. Simulation of the building roof for the future installation of a Solar PV or Solar thermal system to be “Solar Ready”.  See Approval Letter.

California Energy Commission

Approved for Title 24 Non-residential Compliance. 

Florida Building Commission

New York State

Approved for Energy Code Compliance.

Regulations/Rating Systems

IES offers more approved software solutions for compliance than any other vendor. Covering multiple building regulations and rating systems across the globe.

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