Darwin Living Lab House Comfort Ratings

The Department of Infrastructure, Planning and Logistics and CSIRO co-led a Darwin Living Lab project to develop new voluntary comfort ratings for Darwin residential building designs.

Current energy ratings assess energy use when air conditioners are in use. The new comfort ratings assess the comfort of Darwin living room and bedroom designs when no air conditioning is used.

The comfort ratings:

• complement the current energy ratings used to demonstrate compliance with National Construction Code energy efficiency requirements
• are for voluntary use for design optimisation
• are provided for Darwin (and other Top End) postcodes in a trial version of CSIRO’s accredited nationwide House Energy Rating Scheme (NatHERS) software, AccuRate

Comfort Rating Certificate

• Comfort indicators assess how thermally comfortable living areas and bedrooms are without air conditioning in NatHERS Climate Zone 1 (including Darwin)
• The "Comfort Rating" for each room is based on the predicted annual Degree hours of Discomfort above the relevant Comfort Threshold. That is, the sum of all Degrees of Discomfort when the room is assumed to be occupied in a year. The higher the rating out of 10 the better.
• The "Percentage of Time Comfortable" is the predicted proportion of time conditions in each room are below the relevant Comfort Threshold during occupied hours.
• "Worst Hour" provides the predicted Degrees of Discomfort above the relevant Comfort Threshold for the worst hour of the year, for that room, during occupied hours. Timing of Worst Hour will vary between rooms.
• Degrees of Discomfort unit of measurement is Effective Temperature (degrees Celsius). Methodology considers the impacts of air and surface radiant temperatures, humidity, natural ventilation and air flow from ceiling fans.
• Living area and bedroom Comfort Thresholds differ and vary by month. The Comfort Thresholds are based on an ASHRAE Standard 55-2020 formula (modified for Darwin) which takes into account how people acclimatise to the average outside temperature each month as well as occupant clothing levels and metabolic rates
• Clothing levels and metabolic rates are different for living areas and bedrooms and based on research results.
• Occupied hours are the same as assumed for Energy Star Ratings - living zones: 7am - midnight; and bedrooms: 4pm - 9am.
• Kitchen - Living room thermal loads assume the same cooking appliance heat loads used in Energy Star Ratings

Explanatory notes

Industry and community opportunities to discuss the project included:

• A project presentation and workshop at the Darwin Living Lab Symposium on 3 August 2022.
• A project completion Darwin Home Comfort Rating Forum on 24^th March 2023

The Darwin Living Lab has approved funding for a comfort rating roll-out project.  This project is being managed by CSIRO and will allow comfort ratings to be provided by house energy rating assessors when they are energy rating Darwin residential building designs.

Commencement of the project is scheduled for early 2024.  More information will be made available on the Darwin Home Comfort Rating – Darwin Living Lab (csiro.au) website

Information for assessors on how to upload output files from any accredited NatHERS software into the trial version of AccuRate is at: Thermal comfort rating rollout – resources for assessors – Darwin Living Lab (csiro.au) website

Accredited NatHERS software providers are being encouraged to integrate the comfort rating methodology into their software.

For more information

Visit Csiro website.

Contact

DIPL Project Manager Johanna Kieboom 
email: Johanna.Kieboom@nt.gov.au
Call: 08 8999 2506.