Energy Action is Australia’s leading energy management consultancy, delivering efficiency in environmental and financial outcomes. In 2018, Energy Action was engaged to provide analysis and recommendations for Section J of the National Construction Code (NCC) 2019, which included Section J6 for Artificial Lighting.
Section J of the NCC sets out rules for energy efficiency for all building services. The NCC is referenced by state and territory law, making it mandatory to comply with NCC requirements when designing and constructing buildings in Australia.
Cynthia Jolley-Rogers, a lighting consultant for Energy Action, was engaged by the Australian Building Codes Board (ABCB) to test the capacity to increase the stringency for maximum allowable Illumination Power Density (IPD) based on the use of LED. IPD is the number of watts required per square metre to light a space. Under this scope of works, Energy Action provided recommendations for updating the text in Section J6 of NCC 2019. These recommendations were developed to address changing lighting technology and increasing energy efficiency needs.
With some developments still classified, Cynthia describes Energy Action’s findings in Section J6 for NCC 2019, which are currently in the public realm. “When the public comment draft of NCC 2019 was released, the ABCB engaged with the lighting industry to understand the impact of the proposed changes,” explains Cynthia.
Cynthia reveals that the ABCB called for case studies as examples of how the lighting industry could reduce the IPD in their designs and show areas where the changes would impact future designs adversely. Ten case studies were received from four different companies (participants of the case studies were promised a degree of privacy to protect their IP).
Conclusively – track lighting was most impacted by the draft. Cynthia reveals; “The calculations required for the track lighting used up too great a portion of the allowable IPD for the space.” She states that this subsequently locked the designer into using a small amount of track lighting and no other luminaire types, or to not using track lighting at all.
The proposed changes for track lighting were also discussed with lighting designers at a Canberra branch IES technical workshop in great detail. “The logic was that the code was attempting to lock down the power consumption of track lights to prevent the installation of new luminaires after the design had been signed off as meeting the code,” explains Cynthia. “It was thought by those who had written the earlier versions of the code that since track lights do not require an electrician to install them, that they were open to flouting the system”.
However, the lighting industry argued that once a design is installed it remains the same for many years until a retro-fit occurs. The industry consensus was that only in spaces with temporary lighting installations (such as galleries and function centres) are track lights regularly moved around and removed or added from the track.
“In most environments, the power consumption remains static because (even if the lights are moved around), the original quantity remains the same,” comments Cynthia. She reveals that the fear track lights could be added after the design has been signed off, as meeting code was no more valid than anyone adding lights to an installation after it’s been signed off. “Both are possible, and in reality, one does not occur any more frequently than the other.” From these findings, and the workshop Energy Action recommended – the track lighting clause for NCC 2019 was removed.
Further case studies were undertaken on the IDP in restaurants, retailers, laboratories, offices and storage spaces. “The restaurant case studies revealed that they could not achieve the proposed IPD of 6W/m²” reveals Cynthia. Although the restaurant lighting designs varied in energy intensity – even the least energy intensive did not achieve the proposed new limit. Off the back of the restaurant case studies, and further discussions with the lighting industry, the ABCB decided to raise the maximum IPD in NCC 2019 for restaurants to 16W/m² – which was down from 18W/m² in the existing code.
It was noted that on a space by space basis, the restaurant designs did not conform to NCC 2016, but they did when the spaces were assessed as a whole. “This method of offsetting the lower power use in some spaces against other spaces to achieve an overall conformity, is the driver behind the use of the performance method,” comments Cynthia. “This is encouraged to enable clever use of overall efficient design in combination with creative elements.”
The retail case study provided was the common area of a shopping mall. “Even though this was not based on an actual shop, it was a valid case study as it showed that the proposed maximum IPD of 2.5W/m² was woefully inadequate for this space type,” comments Cynthia. These findings then prompted a conversation between the lighting industry stakeholders about what would be required to light a retail space. The discussion resulted in the proposed IPD being raised to 16W/m² – down from 22W/m² in NCC 2016.
The designers commented that the laboratory case study did not include shelves and cautioned that labs with shelves would require a higher IPD. Cynthia explains that even when Energy Action multiplied the power consumption of the case study by four, it still complied. “This indicated that even with shelving introduced, the maximum IPD is appropriate,” she reveals. Therefore the proposed IPD for laboratories of 6W/m² will not change in NCC 2019.
For lighting designs in office spaces, three case studies were provided. “All of these designs were effective and elegant,” remarks Cynthia. Two of them conformed to the NCC 2019 proposed IPD of 4.5W/m², proving that it is achievable.
Storage (Vertical Illuminance)
The issue of compliance for vertical illuminance in storage facilities was raised by a case study into a design for an archives space. Cynthia explains the issue is that there is no allowance for vertical illuminance in the code, and this should be addressed.
Cynthia explains that vertical illuminance targets are mentioned only fleetingly in AS1680. The UK’s Chartered Institution of Building Services Engineers (CIBSE) Lighting Codes provide more detailed recommendations for the ratio of vertical illuminance to horizontal illuminance. Based on CIBSE Lighting Codes, the recommended average vertical illuminance level would be one step down in the AS1680 tables from the recommended horizontal illuminance level. “So, for example, an office which has a horizontal target of 320lx would have a vertical target of 240lx,” she confirms.
“The case study is targeting 320lx on the verticals and the floor,” she discusses. This specification differs from CIBSE recommendations for vertical illuminance because it requires the same illuminance on both the vertical and horizontal planes. While the necessity of this requirement is arguable, it does highlight the issue of maximum IPD for vertical illuminance. “In NCC 2019 an allowance of 4.5W/m² is proposed for an average of 320lx.” Since a higher IPD is required to achieve vertical light levels as opposed to horizontal light levels, Energy Action has proposed an extra allowance in Section J6 when a vertical illuminance is targeted.
Energy Action recommended to the ABCB that explanatory notes be included in the NCC 2019 to state that the maximum IPD allowances were for horizontal illuminance only and that for vertical illuminance targets designers should use the maximum IPD one level up from the IPD stated for that horizontal value. Using this method, the archive would use the 320lx to 400lx maximum IPD allowance which is 6W/m², and the design would conform.
Cynthia elaborates that since the NCC Section J6.2a table and explanatory notes are heavily based on AS1680, the failure of the standard to address vertical illuminance means that the ABCB’s hands are tied. “They need the lighting industry to show the way on this issue, so it looks like this recommendation will not be implemented in the NCC 2019,” she remarks. In light of this, the treatment of vertical illuminance in both the NCC and in AS/NZS1680 will be an issue which will require further analysis and discussion by the lighting industry.
LEDs mature and energy use changes, along with the expectation from light. The best outcome from the NCC in the adjustment is a careful balance between performance, design intent and energy efficiency which reflects modern technology.