2.3.2 The actual building
The actual building allows you control over the following aspects of the design, which it shares with the real building.
Data shared between actual building and real building:
· Location
· Geometry (including orientation and glazing)
· Constructions
· Most system characteristics including renewables
The actual building differs from the real building in terms of its occupancy and plant operation, which for the purpose of UK ratings analysis are forced to standard patterns linked to the activity associated with each room. The data in this category is:
Activity (NCM Template) Room Data:
· Occupancy
· Equipment gains
· Lighting illuminance levels (these, however, are subject to some flexibility, as well as options on control)
· Room conditioning (heating and cooling set points and operation periods)
· Minimum ventilation rates
For the purpose of UK ratings analysis, this data is outside your control and cannot be edited. Note that these attributes are present in the Room Template for use in the Apache module analyses, but the settings appearing there are overridden in the ratings analysis.
The standard settings for VE Compliance are brought into the room by means of a second template called the NCM Template which is applied in combination with the usual Room Thermal Template. The NCM Template contains the standard operating conditions (as listed above) associated with the room’s NCM activity. For example, a room assigned the activity ‘Open plan office’ in a building of type ‘Office’ has an NCM Template called ‘NCM Office: Office (Office: Open)’. This contains the occupancy and equipment gains, the lighting level and profile, the room conditioning settings and the minimum ventilation regime laid down as standard for NCM assessments of an open plan office. NCM Templates appear in the list of Room Templates in the Template Manager, where they can be examined in detail.
The activity (sometimes called the NCM activity) is assigned to the room on the Room Data Building Regulations tab, and may optionally be specified by means of the corresponding attribute in the Room Template. The activity, which is always associated with a particular building type, exists solely for the purpose of building regulations and is only used by VE Compliance. Setting the room activity automatically assigns the correct NCM Template and all the data associated with it. The name of the NCM template, together with that of the room template, can be seen displayed on the General tab of the Room Data dialog.
Not all the Room Data is set by the NCM Template. Just as in the Apache module, each room in VE Compliance has a Room Template, and this sets the parts of the Room Data that are not covered by the standard activity settings – namely:
· System characteristics
· Measures to improve the efficiency of lighting systems
· Parameters affecting infiltration
The Room Data displayed and used in VE Compliance is thus drawn partly from the NCM Template and partly from the Room Template, as follows.
The data on the Building Regs tab is entirely supplied by the user, with the exception of the NCM Template specifying the NCM activity (which the user may override).
The data on the Room Conditions tab is drawn entirely from the NCM Template. These parameters, which include set points and operation times for heating and cooling plant and hot water demand, are fixed for ratings analysis by the room activity, and override the corresponding settings in the room template.
The data on the System tab is drawn entirely from the room template. The system parameters are under your control, and may be adjusted as part of the process for achieving compliance.
The data on the Internal Gains tab is, with one permitted exception, drawn from the NCM Template. Occupancy and equipment gains form part of the standard pattern for the activity. Lighting operation must also follow the pattern laid down for the activity, and must deliver a given minimum illuminance, but here it is permitted to adjust the power consumption to reflect the actual lighting design. It is also permitted to implement daylight-linked lighting control by means of an approved simplified analysis (specified via an option on the Building Regs tab) or other means.
The data on the Air Exchange tab is drawn partly from the room template and partly from the NCM template. The NCM template stipulates ventilation rates for the activity, and these appear as Auxiliary Ventilation air exchanges, replacing any air exchanges of this type appearing in the room template. Other types of air exchange – those of type Infiltration and Natural Ventilation – are taken from the room template.
By applying these rules, VE Compliance automatically sets the attributes that are laid down by the room’s NCM Activity, while giving you control over those aspects where good design can produce energy and carbon savings – namely system performance, infiltration (air-tightness) and ventilation strategies involving the use of outside air for cooling. To this list can be added improvements to the building fabric and system characteristics, which of course do not feature in the room template data.
It should be added that wherever the room template is mentioned above, there is (as usual) the option to override the template settings manually in individual rooms or groups of rooms. However, NCM template settings cannot be overridden in this way, except in the special case of lighting gains.
System characteristics for the actual building (which it shares in the main with the real building) are set by means of Apache Systems, or optionally ApacheHVAC systems. A suitable set of systems should be created and assigned to groups of rooms. The ‘UK NCM system data wizard’ facilitates this process and allows the system characteristics to be specified using an iSBEM-like interface.
