ASHRAE 90.1 (2010): Service Water Heating tab

Contains controls used to view prescriptive option compliance results for the Service Water Heating portion of the ASHRAE 90.1 (2010) requirements.

Water heating requirements are specified in section 7 of the ASHRAE 90.1 (2010) standard, and include general and mandatory provisions, the Prescriptive Path and the Energy Cost Budget Method compliance path options.

Tip: You can open the Results Viewer utility to step through the calculations for displayed results by selecting the result value and clicking for more information (as prompted).

Setting	Description
Service Water Heating	Displays prescriptive results for the service water heating systems in the project building. Service water heating is the heating of water for domestic or commercial purposes other than space heating and process requirements.
Water Heaters	Displays prescriptive results for the water heater systems in the building. Qualifying water heaters are those heated vessels which provide hot water for a use that is external to the heating and cooling systems of the building. Equipment type – Lists all the water heater types in the building. Water heater types can be electric heaters (including heat pump water heaters and instantaneous heaters), fuel-fired storage heaters (gas or oil), fuel-fired instantaneous heaters (gas or oil), fuel-fired pool and spa heaters. Heaters must be of a certain size to qualify based on definitions in the standard. Input Rating – Lists the rated power input for each water heater. Sub-Category or Rating Condition – Lists the performance requirements for each water heater in the building. Volume – Lists the volume of each water heater vessel. Energy Factor or Et – Lists prescriptive results for the factors that determine water heater thermal efficiency for each water heater in the building. Et refers to the combined effects of thermal efficiency and standby losses based on a standardized DOE (US Department of Energy) test in which the ratio of thermal energy transferred to the water (by the heater) to the energy input (required by the heater) is measured. Rated – Lists the DOE energy factor for each water heater in the building. Required – Lists the required energy factor for compliance with the standard for each water heater. Standby Loss – Lists prescriptive results for the factors that determine water heater standby loss for each water heater that serves to provide heat for spaces and water. To comply, the standby loss should not exceed the maximum value calculated by using the definitions and required tests specified in the standard. The requirements are intended to regulate the use of these types of systems for water heating alone after the heating season is over. Energy is wasted in these systems because they are utilizing an oversized boiler (sized to concurrently heat spaces and service water) during those times of the year. Rated – Lists the rated standby loss determined by tests in the factory or the field as required by the standard for each eligible water/space heater in the building. Required – Displays the calculated maximum standby loss for each eligible each eligible water/space heater in the building. Pass/Fail – Displays an overall result of the building’s compliance with the Service Water Heating requirements prescribed by the standard.

Setting

Description

Service Water Heating

Displays prescriptive results for the service water heating systems in the project building. Service water heating is the heating of water for domestic or commercial purposes other than space heating and process requirements.

Water Heaters

Displays prescriptive results for the water heater systems in the building. Qualifying water heaters are those heated vessels which provide hot water for a use that is external to the heating and cooling systems of the building.

Equipment type – Lists all the water heater types in the building. Water heater types can be electric heaters (including heat pump water heaters and instantaneous heaters), fuel-fired storage heaters (gas or oil), fuel-fired instantaneous heaters (gas or oil), fuel-fired pool and spa heaters. Heaters must be of a certain size to qualify based on definitions in the standard.
Input Rating – Lists the rated power input for each water heater.
Sub-Category or Rating Condition – Lists the performance requirements for each water heater in the building.
Volume – Lists the volume of each water heater vessel.
Energy Factor or Et – Lists prescriptive results for the factors that determine water heater thermal efficiency for each water heater in the building. Et refers to the combined effects of thermal efficiency and standby losses based on a standardized DOE (US Department of Energy) test in which the ratio of thermal energy transferred to the water (by the heater) to the energy input (required by the heater) is measured.
- Rated – Lists the DOE energy factor for each water heater in the building.
- Required – Lists the required energy factor for compliance with the standard for each water heater.
Standby Loss – Lists prescriptive results for the factors that determine water heater standby loss for each water heater that serves to provide heat for spaces and water. To comply, the standby loss should not exceed the maximum value calculated by using the definitions and required tests specified in the standard. The requirements are intended to regulate the use of these types of systems for water heating alone after the heating season is over. Energy is wasted in these systems because they are utilizing an oversized boiler (sized to concurrently heat spaces and service water) during those times of the year.
- Rated – Lists the rated standby loss determined by tests in the factory or the field as required by the standard for each eligible water/space heater in the building.
- Required – Displays the calculated maximum standby loss for each eligible each eligible water/space heater in the building.
Pass/Fail – Displays an overall result of the building’s compliance with the Service Water Heating requirements prescribed by the standard.