The Prescriptive Calculations group contains tools used to perform prescriptive calculations for compliance using standards such as the ASHRAE 90.1 and ASHRAE 62.1 standards.

ASHRAE 90.1 Purpose

To provide the minimum requirements for the energy efficient design of buildings except low-rise residential buildings. This includes all new buildings, additions and retrofits. It does not include single family houses, low-rise multi-family residential buildings, manufactured or mobile homes, buildings that do not use electricity or fossil fuels, and buildings that use electricity or fossil fuels mainly for industrial or manufacturing purposes.

ASHRAE 90.1 Scope

Regulate the building envelope, the building HVAC equipment, building service water heating equipment, electric power distribution and metering, and building lighting (interior and exterior).

ASHRAE 90.1 History

The first edition of the ASHRAE 90.1 standard was published in 1975 during the energy crisis of that time. It was updated and re-issued in 1980, 1989,1999, 2001, 2004, 2007 and 2010.

The ASHRAE 90.1–2004 standard was released in 2004, replacing the 1999/2001 standard (2001 was a minor revision, and after 2001, ASHRAE started updating the standard every three years).

The 2004 edition modifications included the addition of Appendix G, a reduction of climate zones (from 26 to 8), and incorporated 31 addenda since the 2001 edition. The ASHRAE 90.1-2007 edition incorporated the modeling of laboratory environments not addressed in the 2004 edition, and appendices written for the 2004 edition.

The ASHRAE 90.1-2010 edition incorporates addenda since the 2007 edition and overall, increases the requirements for energy efficient buildings by 30% over the 2004 standard.

ASHRAE 62.1 Purpose

To specify the minimum ventilation rates and indoor air quality that will be acceptable to human occupants and are intended to minimize the potential for adverse health effects. The standard applies to new buildings, additions to existing buildings, and retrofits identified in the standard. The standard is intended to be used to guide the improvement of indoor air quality.

ASHRAE 62.1 Scope

Regulate ventilation and indoor air quality for all indoor or enclosed spaces occupied by people unless another applicable standard requires more ventilation than the amounts prescribed by ASHRAE 62.1. Kitchens, bathrooms, locker rooms, and indoor swimming pools are also governed by the standard. Although the standard can be applied to new and existing buildings, the standard’s provisions are not intended to be applied retroactively when the standard is used as a mandatory regulation.

ASHRAE 62.1 History

Previously known as ASHRAE Standard 62, the standard was renamed to ASHRAE 62.1 to distinguish it from ASHRAE 62.2 which applies to low-rise residential buildings.The first edition of the ASHRAE 62.1 standard was published in 1973, and has been updated regularly using ASHRAE’s continuous maintenance procedures. According to the maintenance procedures, the standard is continuously revised, potentially multiple times per year, with addenda that are publicly reviewed and approved by ASHRAE. The ASHRAE 62.1 standard was reissued several times after the first edition in 1981, 1989, 1999, 2001, 2004, 2007, and 2010 incorporating addenda, corrections and changes.

In the first edition, the standard required a prescriptive approach to ventilation by specifying both minimum and recommend outdoor air flow rates to obtain an acceptable indoor air quality for a variety of indoor spaces. In the 1981 edition, an alternative procedure, the Indoor Air Quality (IAQ) Procedure, was introduced. This was a performance-based procedure which permitted any amount of outdoor air deemed necessary for compliance if the designer demonstrated that the levels of indoor air contaminants were held below the recommended limits. Today the standard still retains the two procedures for ventilation design, the IAQ Procedure and the Ventilation Rate Procedure. Since 2001, the last time the standard was published in its entirety, it has been updated and revised in a number of significant ways. They are listed in the standard’s informative Appendix H.

PartL 2013 (Technology Preview)

The SBEM (Simplified Building Energy Model) Part L standards is the United Kingdom's prerequisite for energy efficiency accreditation processes and results. The PartL 2013 utility allows you to review and test Part L specific prescriptive calculations for energy and verify the reports compliance with the standards.