Whether or not the reference buildings HVAC system has an economizer depends on the inclusion of an economizer in the proposed buildings HVAC system. If the proposed system has an economizer as per Article 5.2.2.7 the reference is modelled with an economizer as per that article.
Also the type of economizer varies based on system type i.e.
·System 1, 3, 4, 6 & heat pumps – Article 5.2.2.8 (Cooling by Direct Use of Outdoor Air - Air Economizer System)
·System 2, 5 & 7 – Article 5.2.2.9 (Cooling by Indirect Use of Outdoor Air - Water Economizer System)
When an air economizer is required, it must have a high-limit shutoff switch, which matches the proposed. Table A-5.2.2.8 (2) shows the HLSO parameters required in the reference model per air economizer shut off type.
In ApacheHVAC, applicable reference systems have an economizer with the dry-bulb temperature high-limit set to 24°C by default. This will have to be edited by the user depending on the proposed HVAC system configuration. The HLSO type can be changed or the economizer can be disabled by accessing the System Parameters tab of the System Parameters dialog.
Figure 3: System Parameters tab of the System Parameters dialog with economizer option highlighted
When a water economizer is required, it can be added to the associated chilled water loop as per the parameters in Article 5.2.2.9.
