Specification JVb Modelling parameters
This Specification contains the required modelling parameters for JV2 and JV3.
To prescribe how the modelling of the proposed and reference building is to be carried out under JV2 and JV3.
This Specification details the methodology for modelling Performance Solutions under JV2 and JV3. In particular, it details the inputs required for the proposed and reference building.
2. Reference building
The annual greenhouse gas emissions must be calculated for the reference building in accordance with the following:
The reference building must—
comply with Deemed-to-Satisfy Provisions in Parts J1 to J7; and
The external walls must have a solar absorptance of 0.6.
The air-conditioning must—
for 98% of the annual hours of operation, achieve temperatures between—
18°CDB to 25°CDB for conditioned spaces with transitory occupancy; and
subject to (ii), 21°CDB to 24°CDB in all other conditioned spaces; and
if the proposed building has no mechanically provided cooling or has mixed mode cooling, have the same method of control and control set points for non-mechanical cooling as the proposed building.
The infiltration rate in each zone must be—
0.7 air changes per hour throughout all zones when there is no mechanically supplied outdoor air; and
0.35 air changes per hour at all other times.
The artificial lighting must achieve the required maximum Illumination power density in Part J6 without applying the control device adjustment factors.
Minimum Energy Performance Standards must be applied to services not covered by Parts J5 to J7.
To prescribe how the modelling of the reference building is to be carried out.
3. Proposed building and reference building
The annual greenhouse gas emissions must be calculated for the proposed building and the reference building using the same:
annual greenhouse gas emissions calculation method; and
greenhouse gas emissions factors based on either—
the factors in Table 3a; or
the current full fuel cycle emissions factors published by the Australian Government, except, where the greenhouse gas intensity of electricity is less than half the greenhouse gas intensity of natural gas—
electricity is to be weighted as 1; and
natural gas is to be weighted as 2; and
Note to Table 3a: National emissions factors are not applicable to calculations for buildings in the ACT as they do not take into account investments in renewable electricity generation in the national electricity market made by the ACT. Values for the ACT can be found in the ACT Appendix.
location, being either—
the location where the building is to be constructed if appropriate climatic data is available; or
the nearest location with similar climatic conditions, for which climatic data is available; and
adjacent structures and features; and
testing standards including for insulation, glazing, water heater and unitary air-conditioning equipment; and
Fabric and glazing —
quality of insulation installation; and
thermal resistance of air films including any adjustment factors, moisture content of materials and the like; and
dimensions of external, internal and separating walls; and
internal shading devices, their colour and their criteria for operation; and
range and type of services and energy sources, other than renewable energy generated on site; and
assumptions and means of calculating the temperature difference across air-conditioning zone boundaries; and
floor coverings and furniture and fittings density; and
internal artificial lighting illumination levels; and
internal heat gains including people, lighting, appliances, meals and other electric power loads; and
air-conditioning system configuration and zones; and
profiles for occupancy, air-conditioning, lighting and internal heat gains from people, hot meals, appliances, equipment and heated water supply systems based on—
NABERS Energy for Offices simulation requirements; or
Green Star simulation requirements; or
the actual building if—
the operating hours per year are not less than 2 500; or
the daily operating profiles are not listed in Specification JVc; and
supply heated water temperature and rate of use; and
infiltration values, unless the following have been specified—
an intended building leakage of less than 10 m3/hr.m2 at 50Pa; and
pressure testing to verify achievement of the intended building leakage,
in which case the intended building leakage at 50Pa may be converted into a whole building infiltration value for the proposed building infiltration using Tables 4.16 to 4.24 of CIBSE Guide A; and
sequencing for water heaters, refrigeration chillers and heat rejection equipment such as cooling towers; and
representation of clothing and metabolic rate of the occupants; and
control of air-conditioning except—
the reference building must have variable temperature control for chilled and heated water that modulates the chilled water and heated water temperatures as required to maximise the efficiency of the chiller or boiler operation during periods of low load; and
if the controls for the proposed building are not adequately specified or cannot be simulated, the sample control specifications in Appendix B of AIRAH-DA28 must be used; and
environmental conditions such as ground reflectivity, sky and ground form factors, temperature of external bounding surfaces, air velocities across external surfaces and the like; and
number, sizes, floors and traffic served by lifts and escalators.
To prescribe how the modelling of both the proposed and reference building is to be carried out.
Subclause 3(c)(vii)(D) ofSpecification JVbpermits the profiles and internal heat loads of the proposed building to be used in the calculations provided the operating hours are not less than 2,500 per year. The profiles and loads of Specification JVc, NABERS Energy or Green Star need only be used if the hours of operation are less than 2,500 per year. The reason for permitting the expected profiles and internal loads of the proposed building to be used is that, provided the numbers of hours of operation are reasonable, different hours and loads have minimal impact on the modelled outcome as the same values must be used in assessing the reference building as well as the proposed building.
4. Services — proposed and reference building
For the modelling of services for the purposes of calculating annual greenhouse gas emissions—
system demand and response for all items of plant must be calculated on a not less frequent than hourly basis; and
energy usage of all items of plant must be calculated with allowances for—
part load performance; and
staging to meet system demand; and
energy usage of cooling plant must be calculated with allowances for—
the impact of chilled water temperature on chiller efficiency; and
the impact of condenser water temperature on water-cooled plant efficiency; and
the impact of ambient temperature on air-cooled plant efficiency; and
the energy use of primary pumps serving individual chillers; and
the energy use of auxiliary equipment, including controls and oil heating for chillers; and
thermal losses in the chilled water system; and
the impact of chilled water temperature on thermal losses in the chilled water system; and
energy usage of water heating systems for space heating must be calculated with allowances for—
the impact of water temperature on water heater efficiency; and
the energy use of primary or feedwater pumps serving individual water heaters; and
thermal losses in water heating systems; and
the thermal mass of water heating systems, accounting for thermal losses during periods when the system is not operating; and
energy usage of fan and pump systems must be calculated with allowances for—
the method of capacity regulation; and
the use of either fixed or variable pressure control; and
energy usage of pump systems must be calculated with allowances for the system fixed static pressure head; and
energy usage of auxiliary equipment associated with co-generation and tri-generation systems, including pumps, cooling towers and jacket heaters, must be calculated; and
where the energy usage of the heated water supply for food preparation and sanitary purposes or the energy usage of lifts and escalators is the same in the proposed building and the reference building, they may be omitted from the calculation of both the proposed building and the reference building; and
energy use of a lift in a building with more than one classification may be apportioned according to the number of storeys of the part for which the annual greenhouse gas emissions and thermal comfort level are being calculated.
To prescribe the detailed modelling requirements for the services of both the proposed and reference building.