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IEQ-9 THERMAL COMFORT

 

Credit Interpretation Request

Shell & Core compliance, IEQ-9.

Credit Interpretation Request Number
IEQ9-C-OB1-709

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 methodology for the modelling of HVAC under the IEQ-9 credit is deemed acceptable.

Thermal comfort using PMV relies on 6 key factors as per below, provided air conditioning is provided these are largely the same for air based systems.

Air Temperature – As per notional building, the modelling protocol guide already allows a default air temperature band for buildings where no client brief exists.

Radiant Temperature – This applies to perimeter zones and internal surfaces and is calculated during the simulation. Where internal finishes are not installed, either conservative assumptions are to be made or it is to be shown that tenants are contractually required to install the finishes included in the analysis.

Humidity- This is normally not controlled directly in buildings however provided air conditioning is included in the building this is calculated during the simulation.
Clothing – As defined in the technical manual
Metabolic rate – as defined in the technical manual

Air velocity – 0.14m/s is to be used as per guidance from the Green Star SA - Public and Educational Buildings tool for typical artificially ventilated spaces.
Furthermore, the following is to be considered:


Zoning
IEQ-09 modelling requires rezoning of the building as per existing TC’s. Therefore, since even buildings with defined HVAC zones have to change their zoning to suit the requirements, the current requirements for zoning should be used.

Supply Air Simulation
A constant air volume system can be used as the results would be more conservative than using the variable air volume system of the notional building.

As such, using the methodology above, the building will be able to show thermal comfort improvements.

 

Technical Clarification

Thermal comfort and 'Shell & Core' spaces

Technical Clarification Number
IEQ9-T-OB1-0362

Guidance
2013-07-22

The following guidance is provided for spaces delivered as ‘Shell & Core’, as defined in the Green Star SA Office Design v1 Technical Manual.

The thermal comfort within a mechanically ventilated space is highly influenced by the design of the HVAC system within the space. Where a mechanically ventilated space is not provided with a complete HVAC system, as evidenced through the provision of a fully documented design within the tender documentation (Design rating) or as installed As Built documentation and commissioning reports (As Built rating), compliance with the Credit Criteria cannot be demonstrated.

 

Technical Clarification

HVAC plant operating schedules

Technical Clarification Number
IEQ9-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

Revised documentation requirement - Thermal comfort report

Technical Clarification Number
IEQ9-T-OB1-0387

Guidance
2012-01-20

The following updates the documentation requirements of the 'Thermal comfort report' required for both Design and As Built submission as per Page 85 of the Green Star SA - Office v1 Technical Manual. This update is applicable to naturally ventilated buildings, mechanically ventilated spaces and mixed-mode spaces:

Thermal comfort report prepared by a suitably qualified professional that describes how the credit criteria have been met by -

• Describing the HVAC system (where applicable) and passive design strategies used to achieve thermal comfort;
• Confirming which thermal comfort methodology has been used (i.e. ASHRAE 55-2004 Acceptability Limits or ISO7730 PMV values), with justification for the selection based on the Credit Criteria;
• Describing the software package used for determining thermal comfort levels;
• Describing the weather data used and its source, demonstrating that it complies with the weather data requirements of the Additional Guidance;
• Providing marked-up plan drawings clearly showing the zones modelled for thermal comfort and that no perimeter zone exceeds 4m in depth;
• Providing a tabulated summary of all zones modelled, indicating the area of each and confirming all of the UA has been included in the analysis;
• Confirming the occupancy schedule and total number of hours assessed for thermal comfort;
• Confirming that all modelling inputs are in exact accordance with the modelling presented in Ene-1 Greenhouse Gas Emissions;

Additionally where ASHRAE 55-2004 Acceptability Limits methodology used:
• Confirming all spaces assessed are provided with openable windows, and not provided with mechanical cooling systems;
• Providing a table of the mean monthly temperatures and resulting acceptability range;
• Providing a summary table of all zones assessed for thermal comfort and the hours below, within and above the Acceptability Limits of operative temperatures, clearly demonstrating compliance with the Credit Criteria.

Additionally where PMV ISO7730 methodology used;
• Confirming that the CLO and MET values used are in accordance with the Additional Guidance;
• Demonstrating that the air velocity value selected is justified for the actual system design.
• Providing a summary table of all zones assessed for thermal comfort and the hours below, within and above the stipulated PMV levels, clearly demonstrating compliance with the Credit Criteria.

 

Technical Clarification

Thermal comfort and 'Shell & Core' spaces

Technical Clarification Number
IEQ9-T-OB1-0362

Guidance
2012-01-10

The following guidance is provided for spaces delivered as ‘Shell & Core’, as defined in the Green Star SA Office v1 Technical Manual.

The thermal comfort within a mechanically ventilated space is highly influenced by the design of the HVAC system within the space. Where a mechanically ventilated space is not provided with a complete HVAC system, as evidenced through the provision of a fully documented design within the tender documentation (Design rating) or as installed As Built documentation and commissioning reports (As Built rating), compliance with the Credit Criteria cannot be demonstrated.

 

Technical Clarification

Revised credit criteria for naturally ventilated spaces

Technical Clarification Number
IEQ9-C-OB1-0341

Guidance
2011-11-04

The following updates the thermal comfort credit criteria within the Green Star SA Office v1 Technical Manual for naturally ventilated spaces (only);

Naturally ventilated spaces
Two credit criteria compliance routes are available for naturally ventilated spaces, as follows:

Up to two points are awarded if the internal operative temperatures are within the ASHRAE Standard 55-2004 Acceptability Limits for at least 98% of occupied hours during the year:

• One point for internal temperatures within the 80% Acceptability Limits;
OR
• Two points for internal temperatures within the 90% Acceptability Limits.

OR

Up to two points are awarded if the Predicted Mean Vote (PMV) levels, calculated in accordance with ISO7730 using standard clothing and metabolic rate values as provided, are within the following limits for at least 90% of occupied hours during the year:

• One point for PMV levels between -1 and +1 (inclusive);
OR
• Two points for PMV levels between -0.5 and +0.5 (inclusive).


The use of ASHRAE 55-2004 Acceptability Limits of operative temperature for determining thermal comfort may only be used where the naturally ventilated space satisfies the following requirements:

• The space is equipped with operable windows that open to the outdoors, and can be readily opened and adjusted by occupants of the space;
• The space is not provided with a mechanical cooling system (space heating is permitted however the Acceptability Limits are not applicable when the heating system is in operation); and,
• The occupants of the space may freely adapt their clothing to the indoor thermal conditions.

Where the naturally ventilated space does not satisfy these requirements, the ASHRAE 55-2004 Acceptability Limits cannot be used, and Predicted Mean Vote (PMV) levels calculated in accordance with ISO7730 must be used to determine thermal comfort of the space.

 

Technical Clarification

Perimeter zones - clarification

Technical Clarification Number
IEQ9-T-OB1-0318

Guidance
2011-09-30

For thermal comfort modeling, ‘perimeter zones’ are considered to be zones that are on an external façade surface or an unconditioned space that has external surfaces. For example, zones adjacent to a naturally ventilated unconditioned atrium (i.e. experiencing external conditions) would be considered ‘perimeter zones’, however zones adjacent to internal stair core or storerooms that are entirely surrounded by conditioned spaces would not be considered ‘perimeter zones’. Such zones for thermal comfort modeling may or may not coincide with control zones as defined in the mechanical design

 

Erratum

Green Star SA - Office v1 Technical Manual: Page 83

Erratum Number
IEQ9-E-OB1-0302

Guidance
2011-08-08

Credit Criteria, delete “Up to two points are awarded where a high level of thermal comfort is achived for all of the office UA through any combination of the following:", and replace with: "Up to two points are awarded where a high level of thermal comfort is achived for 95% of the office UA through any combination of the following:"

 

Technical Clarification

CLO and MET values - additional guidance

Technical Clarification Number
IEQ9-T-OB1-0297

Guidance
2011-07-21

The GBCSA wishes to provide further guidance regarding the application of CLO and MET values for thermal comfort modelling. The CLO and MET values detailed on Page 88 of the Green Star SA Office v1 Technical Manual must be used for air conditioned & mixed mode offices AND naturally ventilated offices. These are to remain consistent, irrespective of strategies used to provide comfort. Values for air velocity for air conditioned & mixed-mode offices are not prescribed as those values are highly dependent on the systems installed. Selected values for these strategies must be justified with reference to the system design. For naturally ventilated offices, the values prescribed must be used.

 

Technical Clarification

Zone distribution - clarification

Technical Clarification Number
IEQ9-T-OB1-0298

Guidance
2011-07-21

Where a mechanical design incorporates zones adjacent to a façade which are in excess of 4m deep from the façade, for the purposes of thermal comfort modelling only, these must be divided into a perimeter zone of not more than 4m deep from the façade and a centre/internal zone. This is to accurately account for the influence of heat fluxes and temperatures in the perimeter zone. It is not required that actual HVAC designs incorporate a 4m perimeter zone. The division of a larger zone adjacent to a façade is for modelling purposes only. The thermal comfort result is to be calculated on an area weighted average.

 

Erratum

Green Star SA - Office v1 Technical Manual: Page 85

Erratum Number
IEQ9-E-OB1-0162

Guidance
2011-01-06

Documentation Requirements, As Built table, delete the "Extract(s) from the specification(s)" line item.

 

Credit Interpretation Request

PMV assessment at expected historical maximum and minimum ambient temperatures

Credit Interpretation Request Number
IEQ9-C-OB1-0113

Ruling
2010-11-10

The Credit Interpretation Request (CIR) seeking to assess the Predicted Mean Vote (PMV) values for compliance to the credit criteria at the expected maximum summer and minimum winter ambient temperatures only, based on historical metrological data for the site, is denied.

The CIR Review Panel notes that the PMV measure of thermal comfort is calculated from a range of variables including occupant metabolic rate, occupant clothing levels, radiant surface temperature, zone air temperature, zone humidity and zone air velocity. Many of these variables are constantly changing within the occupied zones of a building due to the combination of external climatic influences (e.g. ambient temperature, solar radiation, humidity etc.), internal loads (sensible and latent) and the response of the building’s HVAC system to these influences to maintain air temperature within the control band and set points. As such, it is possible that although zone air temperature can be maintained within the target control band and set points at the proposed extreme ambient conditions, the influence of the other contributing variables may cause PMV results to exceed the acceptable range prescribed in the credit criteria. This may occur at any occupied hour of the year and is not limited to the worst case ambient conditions (historical or otherwise). Hence hourly simulation is required to assess how many hours of the total occupied hours of the year do the PMV results exceed the acceptable range prescribed in the credit criteria to determine compliance with the credit criteria.

 

Technical Clarification

Definitions - "occupied hours”, “standard hours of occupancy” and "standard working hours"

Technical Clarification Number
IEQ9-T-OB1-0110

Guidance
2010-11-02

For the purpose of this credit, “occupied hours”, “standard hours of occupancy” and "standard working hours" are defined as equivalent and equal to the operational profile of the ‘HVAC plant’ as detailed in the applicable Energy Calculator & Modelling Protocol Guide. This definition is applicable to both mechanically ventilated spaces and naturally ventilated spaces (irrespective of the inclusion of HVAC plant or not). Please note these definitions do not amend the ‘Occupancy’ profiles as defined in the applicable Energy Calculator & Modelling Protocol Guide.

 

Technical Clarification

Documentation amendment

Technical Clarification Number
IEQ9-T-OB1-0085

Guidance
2010-06-17

Based on feedback from the assessors and project teams, the following documentation is no longer required at the time of a Green Star SA - As Built submission for this credit:
* Extract(s) from the specification(s)

All other documentation must be provided as per the Technical Manual at the time of submission.

 

 

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