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ENE-1 GREENHOUSE GAS EMISSIONS

 

Credit Interpretation Request

Energy Modelling Protocol Guide - set criteria central plant

Credit Interpretation Request Number
ENE1-C-OB1-0831

Ruling
2014-10-28

The project team’s proposal for allowing compliance based on set standard criteria of section 5.4 for central plant as per Energy Modelling Protocol Guide is approved.

The GBCSA provides guidance relating to this issue:

Where a project team has shown compliance and submitted Energy Calculator & Modelling Protocol Guide v1.1 under section 5.4 HVAC System Simulation

• The size of the central plant used for the energy calculations in this rating tool must be assumed as equivalent to the peak demand of the development pursuing certification
• The part load curves for the actual central plant shall be applied proportionally to the central plant used for the energy calculations.
• Submitting a CIR will only be required when different methods of apportionment within the guide is proposed.

 

Credit Interpretation Request

Accounting for VRF systems in Ene-1 model

Credit Interpretation Request Number
ENE1-T-OB1-768

Ruling
2014-02-27

1) VRF: Outdoor unit energy consumption
The energy consumption of any outdoor unit shall be determined using the ‘interpolated COP data’ as described in item (3) below and the thermal loads as derived from thermal modeling software.

2) VRF: Indoor unit energy consumption
The energy consumption of any indoor unit shall be determined using the ‘specific fan power’ as described in item (4) below and the supply air rates as described in 5) as proposed by the Project Team.

3) Interpolated COP data (outdoor units)
The interpolated COP data for the outdoor VRF units used for the calculation of the annual energy consumption of all the outdoor VRF units included in the project is to be derived from the manufacturer’s product data for –

• All outdoor unit models or types included in the project such that each outdoor unit model or type has a unique interpolated COP data set based on the manufacturer’s product data for that unit;

4) Derived Specific Fan Power (indoor units)
The derived specific fan power for the indoor VRF units used for the calculation of the annual energy consumption of all the indoor VRF units included in the project is to be derived from the manufacturer’s product data for –

• All indoor unit models or types included in the project such that each indoor unit model or type has a unique specific fan power based on the manufacturer’s product data for that unit;

5) Derivation of zone supply air rates
The derivation of zone supply air rates, to which the specific fan power, as outlined in item (4) above, is applied to determine the fan energy consumption of the indoor VRF units, must be determined through modeling the HVAC system as a Constant Volume (CV) system.

6) Treatment of sub-systems
As part-load conditions, thus part-load performance, will vary depending on each sub-system required to serve the different parts of the building that have been connected to that sub-system, it is an unacceptable methodology to aggregate the thermal loads of all zones within the thermal modeling. As each sub-system will have a different installed heating/cooling capacity and the thermal loads within each space will not be equal, each sub-system will have different part load conditions, it is required that each sub-system be post-processed using the methodology approved in item (1) above, individually to account for this. This post-processing method approved in item (1) above must clearly reference the part-load conditions derived from the peak load within the sub-system and the thermal loads of the zones within the sub-system.

 

Credit Interpretation Request

Shell & Core compliance, ENE-1.

Credit Interpretation Request Number
ENE1-C-OB1-708

Ruling
2013-09-26

The GBCSA note that where buildings are delivered as ‘Shell & Core’ or where tenant layout designs are not yet defined, the following proposed methodology for the modelling of HVAC under the ENE-1 credit, is deemed acceptable for buildings to claim savings for load reductions via improved building fabric and for selection of a higher efficiency chiller.
As per Technical Manual guidance for Ene-1 modelling, “all assumptions must be conservative and documented clearly and consistently”.

Heating and Cooling Setpoints
These can be entered as per the notional building. The modelling protocol guide already allows this for buildings where no client brief exists.

Zoning
IEQ-09 zoning requirements may be applied to both the notional and actual buildings.

Supply Air Fan Energy Use
Two alternative methodologies can be used;

Use the notional building fan system as the air side HVAC component. This is conservative since the notional building is considered to represent the minimum system requirement as per SANS.

OR

Where a central chiller is installed, and tenants are contractually required to install Fan Coil Units linked to this central chiller, documentation from the developer outlining the system must be provided as well as the contractual requirement to install Fan Coil Units. The GBCSA understand that research exists that shows that the specific fan power of fan coil units typically never exceeds 0.8w/l/s, this specific fan power along with the air delivered to provide the required cooling can thus be used to calculate annual energy use.

Cooling and Heat Rejection
Where a chiller has been selected for the building, the as-designed / installed chiller must be used with all its attributes to calculate savings in ENE-01.

In summary, using the methodology above, the building will be able to claim savings for load reductions via improved building fabric and for the selection of a higher efficiency chiller.

 

Technical Clarification

Proposed methodology for modelling VRF/VRV systems (This TC supersedes ENE1-T-OB1-0097 issued on 2010/08/18)

Technical Clarification Number
ENE1-T-OB1-0710

Guidance
2013-06-14

Projects that make use of modelling software which includes a simulation for variable refrigerant flow (VRF) or variable refrigerant volume (VRV) systems do not need to submit a Technical Clarification to the GBCSA prior to submittal when modelling these systems in the actual building energy model, provided that the following are met:
- The modelling package is compliant with the ‘simulation package’ requirements of the Green Star SA – Office v1 Energy Calculator and Modelling Protocol Guide.
- The modelling report clearly indicates all the inputs used within the model and demonstrates through contract documentation and product datasheets that these inputs accurately represent the system installed.

Projects using methodologies for modelling of VRV/VFR systems that are not integral to the simulation package must submit a Technical Clarification to the GBCSA prior to submittal, outlining the proposed modelling methodology for approval.

 

Technical Clarification

Proposed methodology for modelling VRF system

Technical Clarification Number
ENE1-T-OB1-700

Guidance
2013-06-13

The technical clarification seeking approval to use the Daiken VRV Systems Plug in tool as the proposed methodology for modelling the VRV and VRF system is approved on condition that the modelling report clearly indicates all the inputs used within the plugin and demonstrates through contract documentation or product datasheets that these inputs accurately represent the system installed.

 

Technical Clarification

Carbon Monoxide (CO) monitoring on basement fans

Technical Clarification Number
ENE1-T-OB1-0636

Guidance
2013-02-13

Where CO monitoring is used to control the air flow of basement fans, the calculation of the required air flow rates and associated energy savings must be based strictly in accordance with a recognised best practise standard or guideline, e.g. ‘2011 ASHRAE Handbook – HVAC Applications’.
The calculation methodology must at a minimum be based on the following inputs:
• Acceptable level of contaminants in the parking facility
• Number of cars in operation at various times over a 24 hour period
• Length of travel and operation time for cars within the car-park
• CO emission rate for a typical car under various conditions
• Total volume of the parking facility


Documentation Requirements:
Within the Energy Modelling Report, the project team must;
• Clearly state the source of the calculation methodology used (recognised best practise standard or guideline).
• Describe the calculation inputs used for each of the items above.
• Provide a description of how the ‘number of cars in operation at various times over a 24 hour period’ and the ‘length of travel and operation time for cars within the car-park’ are a representative or conservative representation of the expected traffic profile for the building.

In addition, the project team must state in the Energy Modelling Report how the following issues have been taken into account within the calculations:
• Accounting for the contaminant level of outside air drawn into the basement;
• Accounting for building form and position of sensors and the effect this may have on operation of the system; and
• Providing efficient, adequate airflow throughout the structure.

The project team must demonstrate with supporting contract documentation (Design rating) or commissioning records (As Built rating) that the CO sensors are set according to the levels used within the calculations.

Note that the project team need not submit the full calculations within the Energy Modelling Report, but simply the confirmations and inputs requested above.

 

Technical Clarification

HVAC plant operating schedules 

Technical Clarification Number
ENE1-T-OB1-0597

Guidance
2012-11-05

Should operating schedules of HVAC equipment be used as part of the energy performance or thermal comfort strategy , e.g. night flushing or early start-up of HVAC plant, the actual HVAC plant operating schedules for the related equipment as supported by tender documentation (Design) or commissioning data (As Built) may be used for the Ene-1 actual building modelling and IEQ-9 credit modelling.

Please note that if any overrides over timer based controls are included in the system (e.g. CO2 or temperature overrides) these should be accounted for accurately or assumptions conservatively justified – alternatively the HVAC plant operating schedules in the energy modelling protocol should be used.

Note that for the Ene-1 notional building, the HVAC plant operating schedules in the energy modelling protocol should be used.

 

Technical Clarification

Supply air Fans and Fresh air Fans (Note this TC replaces ENE1-T-OB1-0374)

Technical Clarification Number
ENE1-T-OB1-585

Guidance
2012-10-01

This serves to clarify the HVAC modelling requirements for the notional building with respect to supply air fans and fresh air fans (As detailed in Table 6 of the Energy Calculator and Modelling Protocol Guide v1.1).

The system to be modelled for the notional building consists of constant volume fresh air fans supplying fresh air to the building as well as variable volume indoor supply air fans supplying conditioned air.

Note that the Fresh Air Fan requirements are detailed in the first row of the table on page 10 of the Energy Calculator & Modelling Protocol Guide v1.1. (Note that these requirements are not to be omitted as stated by the now replaced TC 374)

The Supply air fan requirements are detailed in the last row of the table on page 9 of the Energy & Modelling Protocol Guide v1.1.

 

Credit Interpretation Request

 

Credit Interpretation Request Number
ENE1-T-OB1-0420

Ruling
2012-06-18

The CIR Review Panel has assessed the Credit Interpretation Request (CIR) relating to the occupancy sensor provision for lighting in external areas and parking areas and has provided the following ruling back to the GBCSA:

The CIR Review Panel notes that for external areas and car parks, in order to make use of the “Internal lighting with presence controls” schedule in Table 17, Appendix C of the Green Star SA – Office v1 Energy Calculator & Modelling Protocol guide, presence detectors need no longer be provided to a specific density, but the project team must show that presence detectors have been installed, and at least 70% of the car park lighting and/or external lighting (by installed power not number of fixtures) is linked to presence detectors. Please note that enclosed spaces such as storeroom need not be connected to occupancy sensors. The project team should also demonstrate that each floor is separately controlled and that external lighting is controlled separately to that of the car park.

Documentation Requirements:
The project team is required to submit contract documentation (drawings and/or specifications) confirming that lighting controls have been specified / installed in compliance with the requirements listed above i.e. indicating that each floor is individually controlled and that the required % of lighting is linked to occupancy sensors. The project team must also clearly show in the Energy Report the detailed calculations showing that 70% of their total wattage is controlled by presence detectors.

 

Technical Clarification

Should new SANS 204:2011 standard apply for Ene-1 compliance or is SANS 204:2008 acceptable?

Technical Clarification Number
ENE1-T-OB1-437

Guidance
2012-05-23

The GBCSA can confirm that in terms of the SANS 204 standard referenced in the Green Star SA – Office v1 rating tool, the tool currently references SANS 204:2008 and as such, projects are only required to comply with SANS 204:2008, and not SANS 204:2011 for the purposes of compliance with the Ene-1 credit. If project teams however wish to use the SANS 204:2011 standard, it should be shown how this would result in equal or conservative Ene-1 results when compared to SANS 204: 2008.

 

Technical Clarification

ENE-01: Weather Data - Weather Analytics (WxA)

Technical Clarification Number
ENE1-T-OB1-462

Guidance
2012-03-27

For the purposes of energy modelling for the Ene-1 credit, in addition to the Meteonorm software, weather data can also be obtained from the Weather Analytics (WxA) platform.

See http://www.wxaglobal.com/.

 

Technical Clarification

Energy modelling - Calculation of total U-values of windows/glazing assemblies

Technical Clarification Number
ENE1-T-OB1-0352

Guidance
2012-01-12

For the purposes of energy modelling for the Green Star SA - Office v1 Ene-1 credit, for the actual building, where an overall window (whole glazing) U-value is not known, but the project team does have glazing U-values from the manufacturer, calculations may be performed to take account of the thermal conductance of the frame and thus ascertain the overall window U-value. Industry standard U-values for various frame materials such as those published by the CSIRO (Commonwealth Scientific and Industrial Research Organisation - Australia) may be used for this purpose. Where calculations of the overall window U-values are performed, the following must be clearly shown in the Energy Modelling Report.

• Details of composite U-value calculations.
• Individual element U-values used in the calculation and their source.
• Justification of glazing and frame areas used in the calculations.

Where the manufacturer U-value for the glazing is not known, the U-values from the table on ‘Worst-case whole glazing element performance values’ given in SANS 204:2011 should be used in the model.

 

Credit Interpretation Request

Intellectual property - trigeneration system design documentation

Credit Interpretation Request Number
ENE1-C-OB1-0353

Ruling
2012-01-12

The Credit Interpretation Request (CIR) seeking approval to substitute extracts of tender documentation with a statement of confirmation from the design engineers to protect the intellectual property of the tri-generation system is conditionally approved.

The CIR Review Panel notes that the Project Team is permitted to request alternative forms of documentation where they wish to protect intellectual property, however sufficient documentation must be submitted to satisfy the GBCSA of inclusion within the design. A statement of confirmation, prepared and signed by a suitably qualified professional responsible for the design of the tri-generation system, may be submitted provided the following information is confirmed:

• Estimated hourly electrical energy produced by the plant;
• Estimated electrical energy consumption of plant itself;
• Estimated hourly heat supply to the absorption chiller;
• Estimated hourly heat supply for DHW;
• Estimated hourly heat supply for tempering of fresh air;
• Size of auxiliary pumps in system and energy consumed
• Estimated amount and type of primary fuel consumed;

In addition;
• Size/capacity of major components of the system, including the generators, the absorption chillers and heat exchangers (i.e. kW).

In addition to the statement of confirmation, extracts of tender documentation must be submitted to confirm the inclusion of the tri-generation system within the design. This must be of the form of;

• Tender architectural plan drawings showing the location/space allocation of the trigeneration system;
OR
• Tender mechanical services plan drawings showing the location/space allocation of the trigeneration system.

The CIR Review Panel notes that as the project is registered for a Design certification, information contained on the statement of confirmation must be based on calculated estimates. It is not acceptable to use actual measured performance data from the tri-generation system (if operational).

 

Credit Interpretation Request

Automated daylight control for daylight dimming or switching - approved methodology.

Credit Interpretation Request Number
ENE1-C-OB1-0383

Ruling
2012-01-12

The Credit Interpretation Request (CIR) seeking approval for the proposed methodology for the control of light fittings via automated daylight control, for daylight dimming or switching is conditionally approved. The CIR Review Panel notes that proposed methodology is robust and well researched to predict energy savings from an automated control system. However within the submission, the Project Team must clearly identify the correlation between the lighting zoning and the HVAC zoning in the model.

The CIR Review Panel confirms that the Documentation Requirements which must be demonstrated within the submission are;
- Daylight modelling report in strict compliance with IEQ-4 Daylight (to demonstrate the daylight model);
- Tender / As Built Drawings (to demonstrate sensor positions and control zones);
- Extract(s) from specifications (to correlate the control methodology with the actual design);
- Energy modelling report (to demonstrate that the modelling accurately reflects the design).

Approval is conditional on the following methodology only:

1) The daylight model is established using software that can export to Daysim;

2) Daysim (driving the Radiance simulation engine) is used to establish the hourly daylight availability per grid point on an analysis grid with grid points a maximum of 1m x 1m apart with the first measurement point within half a meter from the façade. The resulting output file contains lux levels for each hour of the year for each grid point. The weather data file used must be compliant with ENE-1 and be the same file used for the ENE-1 modelling so that the daylight results and weather conditions related to the rest of the heat loads are correlated;

3) The data is analysed to establish when daylight levels at 1.5m in from the centre of the glazing or greater, exceeds 2000lux;

4) The same analysis process is then used to establish the hourly daylight availability with the blinds closed with any daylight penetration according to the design features (e.g. light shelves, daylight redirecting blinds etc.);

5) A single daylight availability file is created from the two scenarios of (a) no glare and blinds up and (b) glare and blinds down;

6) The results of this hourly file are then zoned according to the lighting controls. The control point used is the grid point that is reflective of the daylight sensor position;

7) The response of the light system within these different zones (including parasitic power where applicable) is determined according to the power consumption at the differing illumination contribution made by the electric lighting system to the space to make up for what the daylight cannot provide. Control is performed as per the design – either dimming or stepped;

8) It may be assumed that all electric energy consumed by the lighting system is given off as a heat load to the space and an hourly lighting schedule for the entire year for each zone is created and exported into the file format that can be used by the thermal modelling software.

All prescribed documentation requirements must be met as outlined above.

 

Credit Interpretation Request

Control of light fittings via informed user control

Credit Interpretation Request Number
ENE1-C-OB1-0384

Ruling
2012-01-12

The Credit Interpretation Request (CIR) seeking approval for the proposed methodology for the control of light fittings via informed users control is denied.

Although the CIR Review Panel supports design attention to the interface between occupants and control systems within buildings and the potential for resource savings, for the purposes of base-building benchmarking within Green Star SA, the proposed methodology is not deemed acceptable.

The CIR Review Panel notes that “clear and user friendly” instruction signage cannot be considered as an attribute of the base-building (although are to be commended for best practice) and unlike other aspects of Green Star SA where occupant behaviour is assumed based on necessary human physiology drivers (i.e. frequency of amenity use), assumptions pertaining to occupant interaction with control systems (e.g. lighting or HVAC) are highly variable and influenced by multiple factors.
On this basis it is not possible to reliably determine to any extent the benefit gained of continuous and on-going informed users interface with a particular control system for the purposes of benchmarking in Green Star SA further than what is already permitted as per Appendix C of the Green Star SA Office v1 Energy Calculator Guide.

 

Technical Clarification

Supply air fans to be modelled as variable air volume

Technical Clarification Number
ENE1-T-OB1-0374

Guidance
2012-01-03

Replaced by TC ENE01-T-OB1-585

 

Technical Clarification

Post-processing of systems modelling

Technical Clarification Number
ENE1-T-OB1-0314

Guidance
2011-08-23

“The Green Star SA – Office v1 Energy Calculator & Modelling Protocol Guide (Version 1.1.) permits “post-processing” of systems modelling, completed in a spreadsheet program or by hand, provided “full details are submitted”. The GBCSA wishes to clarify that where post-processing methodologies are developed and applied by hand, using common spreadsheet programs, or proprietary software programs, in acknowledgement of intellectual property, “full details” constitute a brief explanation of the concept of the methodology only. It is not required that Project Teams explicitly detail the methodology such to communicate their intellectual property.

Where Project Teams have specifically developed proprietary software to complete post processing, this is deemed equivalent to the use of a “spreadsheet program” as per the Energy Calculator & Modelling Protocol Guide (Version 1.1), and is therefore deemed acceptable. Please note however, the derivation of thermal loads for the building(s) must be completed using simulation software compliant with Section 5.1 of the Energy Calculator & Modelling Protocol Guide (Version 1.1.).

 

Technical Clarification

Internal walls in Office areas

Technical Clarification Number
ENE1-T-OB1-0276

Guidance
2011-06-01

Where internal walls within Office areas are provided as part of the ‘base building provision’ (i.e. will not change based on tenant requirements), project teams may include these within the Green Star SA submission, but should ensure they are included consistently across the submission. (E.g. finishes to these walls may need to be included in the IEQ-13 credit.)

 

Technical Clarification

Car Park Ventilation

Technical Clarification Number
ENE1-T-OB1-0118

Guidance
2010-11-23

Where car parking on basement levels which are partially below ground is to be modelled, the following guidance should be followed for the notional SANS 204 building (refer to Green Star SA – Office v1 Energy Calculator & Modelling Protocol Guide v1.1 item 6.1);

The first basement level (B1) which is partially below ground should be assumed naturally ventilated (i.e. no car park ventilation energy use). For car parking on lower basements (below B1) which are partially below ground and mechanically ventilated in the actual design (if deemed to be required under SANS 10400 parts O & T), the same flow rates as the actual peak design, with a specific fan power of 1.6 W/l/s (per SANS 204-3:2008) should be used. For car parking on lower basements which are partially below ground and naturally ventilated in the actual design (if deemed not to require mechanical ventilation under SANS 10400 parts O & T), these should be modelled as naturally ventilated (i.e. no car park ventilation energy use) in the notional SANS 204 Building.

 

Technical Clarification

Modelling Software

Technical Clarification Number
ENE1-T-OB1-0096

Guidance
2010-08-18

DesignBuilder software interface for the BESTEST-certified Energy Plus modelling software is acceptable for Green Star SA purposes.

 

Technical Clarification

VRF/VRV Modelling (SUPERCEDED by TC ENE1-T-OB1-0710 issued on 2013-06-14)

Technical Clarification Number
ENE1-T-OB1-0097

Guidance
2010-08-18

 

 

Technical Clarification

Occupied space below ground

Technical Clarification Number
ENE1-T-OB1-0089

Guidance
2010-07-07

If the actual building contains regularly occupied space below ground, the notional building must still be modelled as above-ground, with the properties laid out in the Green Star SA - Office v1 Energy Calculator and Modelling Protocol Guide (the Energy Guide). In the case that the actual building contains both occupied and parking floors below ground, the notional building must be modelled with the lowest regularly occupied floor at ground level, and the first basement parking level modelled as naturally ventilated per the Energy Guide. For example, if the actual building contains two regularly occupied floors on B1 and B2, with three levels of parking below (B3 to B5), then the notional building will have the occupied floors as ground and 1st floor, with the parking as B1 (naturally ventilated), B2 (mechanically ventilated) and B3 (mechanically ventilated).

 

Technical Clarification

Shading for notional building

Technical Clarification Number
ENE1-T-OB1-0036

Guidance
2009-05-21

When modelling the notional building, the effects of shading from neighbouring buildings must be included, but the model should not incorporate any shading devices on the building itself. Glazing area for the notional building is then determined as per SANS 204.

 

 

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