This utility allows you to describe the characteristics of heating, ventilating and air conditioning systems using the method implemented in the BRE Simplified Building Energy Model (SBEM). It was developed for use in compliance testing for UK Building Regulations Part L2 (2006), but can also be applied more widely. The system specifications entered here are interpreted into Apache Systems, where they are used for sizing central plant and calculating fuel consumption and carbon emissions. They are suitable for use in Building Regulations compliance tests, ApacheSim, ASHRAE Loads and CIBSE Loads.
Using the UK NCM System Data Wizard
The wizard is accessed using the ‘UK NCM system data wizard’ button on the Apache Systems dialog. The following NCM system types are available for selection:
The five tabs of the UK NCM system data wizard define different aspects of system performance. Each tab is enabled only when relevant to the chosen system type. For example for the type ‘Central heating using water: radiators’ the Cooling system tab will not be editable.
The UK NCM system data wizard translates the inputs into the following parameters which are displayed at the bottom of the wizard and passed back to the Apache Systems:
Heating SCoP
Cooling SSEER
Auxiliary Energy Value
Where appropriate, heat recovery information is also transferred to the selected Apache System.
The system types appearing at the top of the list that involve heating only, and do not specify a ventilation mechanism, are assumed by default to be served by mechanical ventilation. In cases where the building is naturally ventilated, this should be specified on the Apache Systems dialog using the ‘Cooling/ventilation mechanism’ setting.
The following additional guidance is provided in the SBEM documentation, and applies to the analogous settings in the UK NCM system data wizard:
The system type selected in the General sub-tab automatically brings with it some assumptions. For example, whether mechanical ventilation is an integral part of the system and the degree of local time and temperature control that is (or can be provided). The majority of system types used in UK buildings can be found in the system type drop down box. However, there are a few systems which require further guidance:
VRF Systems have been removed - for these systems select 'split or multisplit system with natural ventilation'. You will beed to define a suitbale efficiency. Multisplit is suitable for use with VRF as it is essentially a type of split/multisplit system. If these systems have additional mechanical centilation, then this mechanical ventilation rate should now be selected at room level with a suitable ventilation SFP.
If Chilled ceiling is selected, the default assumotion is that there is displacement ventatilation.
Chilled ceilings with no mechanical ventatilation - select 'Chilled ceilings or passive chilled beams and displacement ventilation' and then set the specific fan power to zero.
Chilled ceiling with mixing ventilation - select 'Chilled ceilings or passive chilled beams and displacement ventilation' and thene use twice the actual soecific fan power in order to capture the effect of the higher ventilation rate.
