ASHRAE Standard 205

ASHRAE Standard 205-2023 is titled "Representation of Performance Data for HVAC&R and Other Facility Equipment" and provides data formats for conveying detailed performance data for different types of equipment used in buildings. The premise is that manufacturers of equipment intended for buildings covered by Standard 205 would put their detailed performance data into that format and make it available to users. BEM software would be able to use data in the Standard 205 formats for the equipment being simulated. This would replace the user trying to interpret information from manufacturers' data sheets into a form acceptable by the BEM software. This data is often inconsistent between equipment manufacturers, and the detailed data for the performance at various part loads and operating temperatures, often needs to be converted into various performance curves. Since different BEM software programs often have different ways of expressing this information, equipment manufacturers rarely try to provide this detailed performance data for any simulation program. If Standard 205 was widely adopted by both equipment manufacturers and BEM software vendors, it would provide the building industry with much more accurate and consistent building energy models. Different data formats are described for each type of equipment that appears in the standard based on a common schema format, and each is called a “representation specification.”

Purpose and Scope

The purpose of Standard 205 is:

“To facilitate automated sharing of equipment performance characteristics by defining data models and data serialization formats.”

And the scope states:

“This standard applies to performance data for any HVAC&R or other facility system, equipment, or component.”

These are both very broad and describe the long-term intention of what will be covered by the standard in the future. In 205-2023, the data formats or representation specifications currently are:

• RS0001 Liquid-Cooled Chiller
• RS0002 Unitary Cooling Air-Conditioning Equipment
• RS0003 Fan Assembly
• RS0004 Air-to-Air Direct Expansion System
• RS0005 Motor
• RS0006 Electronic Motor Drive
• RS0007 Mechanical Drive

Some of these representation specifications are used within others.

• RS0002 Unitary Cooling Air-Conditioning Equipment embeds RS0003 Fan Assembly and RS0004 Air-to-Air Direct Expansion System.
• RS0003 Fan Assembly embeds RS0005 Motor and RS0007 Mechanical Drive.
• RS0005 Motor embeds RS0006 Electronic Motor Drive.

This allows efficient and consistent data representations for sub-components that are likely to be reused in the future. The broad nature of the purpose and scope lets future versions of 205 include both HVAC components as well as building components unrelated to HVAC to be described.

Format

Standard 205 describes the data formats for building components in detail and is based on the JSON format and specifically using the Concise Binary Object Representation (CBOR) format. As an example, the RS0001 Liquid-Cooled Chiller format includes high-level parameters such as:

• model_number
• nominal_voltage
• refrigerant
• net_refrigerating_capacity
• input_power

and many more. It also includes a description of the tabular data representing the performance at different conditions, such as input or “grid” variables of

• evaporator_liquid_volumetric_flow_rate
• evaporator_liquid_leaving_temperature
• condenser_liquid_volumetric_flow_rate
• condenser_liquid_entering_temperature
• compressor_sequence_number

and dependent or “lookup” variables of

• input_power
• net_evaporator_capacity
• net_condenser_capacity
• evaporator_liquid_entering_temperature
• condenser_liquid_leaving_temperature
• evaporator_liquid_differential_pressure
• condenser_liquid_differential_pressure
• oil_cooler_heat
• auxiliary_heat

Adoption

At this point in time, there has been little data published following the formats described in Standard 205 and only limited adoption of using such data by BEM software vendors but more adoption is expected with time.

Additional Resources

Standard 205 at ASHRAE Bookstore

Preview of Standard 205 at ASHRAE

ASHRAE Data page on Standard 205

205 Schema Development on Github

205 Toolkit Development on Github