Air-side system types will be set up automatically depending on the names of the HVAC groups in the source TBD, much like how the system groups depend on the names of the same. If the studio was able to create appropriate system groups for you (previous screen) then it will be able to assign appropriate air-side types.
Right-click on the system group to manually assign an air-side system type from the pop-up menu.
There are three different CAV systems to choose from. There are two types of fancoil, mechanical ventilation without any cooling, VAV, and VRF setups. Other options include active chilled beams, displacement ventilation, extract only, mixed mode, and natural ventilation. There's also an option to model just the internal gains as per the NCM database but without any heating or cooling. This option is called "occupied and unheated".
Demand control ventilation based on occupancy density or gas sensors can be modelled in the actual building for zones with mechanical ventilation. Enhanced ventilation control can be modelled in naturally ventilated zones linked to building management systems, e.g. electronic trickle vents. The associated demand control coefficient will depend on the type of demand control as per Table 14 of the NCM modelling guide. The reduced fresh air rate will be calculated using Eq. 13 of the NCM.
Demand control ventilation with fan speed control for air flow regulation will affect the auxiliary energy calculation. This is not true of damper control.
Demand control ventilation through variable fans with speed control based on CO2 sensors will be modelled in the notional building for zones with mechanical ventilation.
Auxiliary energy is the product of the auxiliary power density and annual hours of operation of the heating system from the NCM Activity database. The auxiliary power density is the sum of the pump and fan power densities.
Three sections are on the right which need to be filled in: BRUKL Details, Components, and System.
The HVAC Type drop-down list under BRUKL Details refers to Table 11 per the NCM modelling guide (2013) and determines whether pump power should be accounted for (LTHW only, LTHW and CHW, or None) and if variable speed pumping will be allowed.
The Pump Config drop-down list refers to Table 12 of the NCM and specifies pump power densities for constant and variable speed pumping.
Where the ventilation system provides heating, cooling, or both heating and cooling, the fan power density will be calculated per zone using one of the equations in paragraph 95, see Eqs. 8-12. Refer to Table 13 in the guide for how the fan power density equations will be assigned as a function of HVAC system type.
See paragraphs 97 and 98 of the NCM for how fan power densities will be determined if the ventilation system does not provide heating or cooling, or if you're modelling extract only systems.
The HVAC type that you select for top-lit zones will determine whether the notional building will be served by direct-fired multiburner radiant heating that will not incur auxiliary energy for fans and pumps. These types include 1) unflued radiant heaters, 2) flued radiant heaters, and 3) multiburner radiant heaters.
Where the HVAC system in the actual building is "wet" the pump power density for the notional building will be 0.3W/m2 for heating only, or 0.9W/m2 if air-conditioned. For dry systems the notional building will not have any pump power.
The fan power density in the notional building will be determined per zone using Eqs. 3-5 where the ventilation system provides heating, cooling, or heating and cooling. If the ventilation system does not provide heating or cooling, or zones are served by local mechanical exhaust only, the fan power density will be determined as per paragraphs 64 and 65 in the NCM modelling guide.
To model a shell and core building you will have to model both the core and shell areas. Which services you use to model the shell areas will be assumed by the user as there are no pre-defined systems to choose from.
For analysis at "as built" stage the proportion of energy associated with shell zones will be ignored in the total energy consumption along with their floor area. Energy generated by renewable sources such as photovoltaics, solar thermal, or wind turbines will be apportioned on an area-weighted basis. Energy form CHP will only apply to core areas. For "as design" stage energy will be accounted for as normal.
Monitoring for out-of-range values can be toggled on and off here. This feature will reduce heating, cooling, auxiliary, and HWS consumption by 5%.
Exercise and Notes
In this example the studio was able to correctly guess the air-side system types because of how the HVAC groups were named in the source TBD. Make sure that your air-side system types are correctly allocated by selecting them on the right-click menu.
For each system we will be monitoring for out of range values, as per the Building Regulations and Building Category topic explains.