UK NCM System Data Wizard
What is the UK NCM System Data Wizard?
This utility was developed for use in compliance testing for UK Building Regulations Part L2 (2006), but can also be applied more widely. It allows you to describe the characteristics of heating, ventilating and air conditioning systems using methods implemented in the BRE Simplified Building Energy Model (SBEM). The system specifications entered in the wizard are applied to 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.
This account of the UK NCM System Data Wizard describes its operation within the framework of simulation-based ratings methods, which are covered in other respects in the appropriate ratings user guides (for example PartL(2013-2014)ApacheSim.pdf). The corresponding utility used within the framework of SBEM-based methods is covered in the guides detailing those methods (for example PartL(2013-2014)VE-SBEM.pdf).
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 seven 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.
Other settings in the wizard, such as those on the Metering Provision tab, affect system performance for ratings purposes without being reflected on the main Apache Systems dialog.
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’ – you will need to define a suitable efficiency. Multisplit is suitable for use with VRF as it is essentially a type of split/multisplit system. If these systems have additional mechanical ventilation, then this mechanical ventilation rate should now be selected at zone level with a suitable ventilation SFP.
- If Chilled ceiling is selected, the default assumption is that there is displacement ventilation
- Chilled ceiling with no mechanical ventilation – 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 then use twice the actual specific fan power in order to capture the effect of the higher ventilation rate.
Heating system
- Heat source
Type of heat generator (e.g. boiler) used in the system.
- Fuel type
Fuel used by the heat generator chosen for the system.
Where the Heat Source has been specified as District Heating the fuel is automatically set to District Heating.
- Tick if this system also uses CHP
Tick to use a CHP system as the base load for this heating system.
- Generator seasonal efficiency
Enter the seasonal efficiency of the heat generator if known. Accept the default if not known.
- Does it qualify for ECAs?
Indicate whether the generator qualifies for ECAs (Enhanced Capital Allowances). Generators on the ECA list can be expected to have improved efficiencies, and this is reflected in the default seasonal efficiency value.
- Tick if this system was installed on or after 1998
This affects the default seasonal efficiency.
Cooling system:
- Type
Type of cold generator (eg chiller) used in the system.
- Power
Choose the size of the cold generator chosen for the system.
- Chiller Fuel Type
Only grid supplied electricity will be available unless one of the heat pump options is selected.
- Generator seasonal Energy Efficiency Ratio (SEER)
Enter the SEER of the heat generator if known. Accept the default if not known.
- Does it qualify for ECAs?
Indicate whether the generator qualifies for ECAs (Enhanced Capital Allowances). Generators on the ECA list can be expected to have improved efficiencies, and this is reflected in the default seasonal efficiency value.
- Generator nominal Energy Efficiency Ratio (EER)
Enter the nominal EER of the heat generator if known. Accept the default if not known.
- Mixed mode operation strategy (SBEM only)
Tick on if a mixed mode operation strategy is in use. This applies to SBEM only.
System adjustment
- Ductwork and AHU leakage
Specify the AHU and Ductwork leakage standards for the system.
- Specific Fan Power for the system
Choose the specific fan power for the system. Note: the default value does not comply with the 2006 building regulations and should not be used for new buildings.
Metering Provision
- Control provision
Choose whether the system has metering provision and whether the metering can warn about “out of range values”.
- Control correction
The used Control Correction factor is displayed here, according to the settings under Control provision
Ventilation
Ventilation
Available cooling/ventilation mechanisms include
- Air conditioning
- Mechanical ventilation and
- Natural ventilation.
However, depending on the selected system type, not all options are available.
For example, if a system type has been selected that allows for a cooling system (Cooling system – tab has been activated), cooling/ventilation mechanism can only be set to Air conditioning.
For those systems the Cooling system tab has not been activated, the user can select between Mechanical and Natural ventilation.
Select the Air supply mechanism from the drop-down list. Note: This option is only available for Cooling/Vent. mechanisms other than Natural ventilation.
Heat recovery
Indicate the type of heat recovery used in the system (if any). Is the Heat recovery seasonal efficiency is known, it can be specified here. A default value is used otherwise.
System controls
Heating System Controls
Tick the boxes provided if they apply to the current HVAC system.
Bivalent systems
A bivalent heating system allows the specification of subsidiary heating systems which supplement the main heating system defined on the ‘Heating’ tab. The subsidiary heating systems may have different fuels and different efficiencies from the main system. A bivalent heating system is one in which the heating is supplied by two different types of heat sources. An example could be a heat pump with a gas boiler for backup.
The grid above enables you to define the characteristics of your bivalent systems. Double click the appropriate cell; Heat source, Fuel, Gen. SEff (fraction) and % Load to edit the default characteristics. Editing these parameters will force the % Load for the primary system and the Overall seasonal efficiency to be re-calculated.
Clicking Add or Delete will add a new system to the table or delete an existing system respectively.
Showers (SBEM Methodology)
Waste Water Heat Recovery Showers is a new feature in SBEM v5.6a. The functionality is available in Part L2 (2013) England, Part L2 (2014) Wales, and Section 6 / 63 (2015) Scotland. WWHRS is not available in any DSM version of UK compliance.
WWHRS can be accessed in the UK NCM data wizard in the Showers tab. This tab defines:
- Number of shower types (by using the add/ remove button to increment or decrement)
- Whether the shower has a heat recovery system WWHRS Present?
- Whether the shower is located over a bath (cubical otherwise) Shower Over Bath?
- If heat recovery is present, a definition of it’s efficiency Heat Recovery Efficiency
- Whether the shower is pumped (so electrical energy can be tracked Uses Pump
- If the shower has a pump, a definition of pump power Notional Pump Power (W)
- Lastly how many individual showers of that shower type are in the building Units