3.1.2 Calculation Methods

The Rating Software shall calculate the annual consumption of all end uses in buildings, including fuel and electricity for:

• HVAC (heating, cooling, fans, and ventilation);
• Lighting (both interior and exterior);
• Receptacles and miscellaneous electric;
• Service water heating;
• Process energy uses;
• Commercial refrigeration systems; and
• All other energy end uses that typically pass through the building meter.

The Rating Software shall perform a simulation on an hourly time interval (at a minimum) over a one year period (8760 hours) with the ability to model changes in weather parameters, schedules, and other parameters for each hour of the year. This is typically achieved by specifying a 24-hour schedule for each day of the week plus holidays.

Calculating Design Loads

The software shall be capable of performing design load calculations for determining required HVAC equipment capacities and air and water flow rates using accepted industry calculation methods for both the proposed design and baseline building design.

Checking Simulation Output for Unmet Loads

The software shall be capable of checking the output of the energy analysis module for the proposed design to ensure that space conditions are maintained within the tolerances specified (maximum of 300 unmet load hours per year).

Adjusting Capacities

For the baseline building (when applicable), the software shall be capable of modifying capacities, temperatures or flow rates for baseline building HVAC system components resulting in excessive unmet loads hours meeting the criteria, following the procedures in Chapter 2.

Error Handling

The software shall identify error conditions when unmet loads fail to meet the criteria, prevent completion of the rating analysis, and provide information to the user describing the error that has occurred and what steps the user should take to remedy the situation.