Investing in a Future-Proof Roof for Highpoint Shopping Centre

To ensure that our assets are resilient to future climate change impacts, GPT completes and considers climate-related risk reviews when making major asset capital expenditure decisions. This includes lifecycle upgrades to plant and equipment at our assets, such as roof replacements.


At our Highpoint Shopping Centre in north-west Melbourne, the Rosamond Road and Aquatic Drive Level 3 roof had reached the end of its useful life. Its replacement was included in a major refurbishment of the centre that commenced in 2019. With a base scope of works that included the replacement of the roof sheeting, guttering and insulation, a climate risk review was undertaken to ensure that the roof selected would have an expected 50 year lifespan.


GPT engaged XDI (Cross Dependency Initiative) to review the physical climate-related risks at Highpoint that might impact the roof replacement under our high emissions scenario (aligned to RCP 8.5) over the medium to long term. Climate modelling was carried out for the probability of business operation impacts and future damage or impairment to the building due to climate hazards including extreme weather events (including floods and severe convective storms), tidal inundation, bushfire, heatwaves, rising average temperatures, and extreme wind.


The assessment identified two physical climate risks that could be addressed through the roof replacement project: intense rainfall and rising average temperatures.


With the increased likelihood of more frequent intense rainfall in the area, the roof structure and pitch were reviewed and identified as sufficient to weather 1 in 100 year rainfall events out to 2070. However, the capacity of the proposed box gutters would be challenged by these events and could lead to water ingress damage to the building and tenancies. Consequently, engineers designed the guttering and overflows to increase their capacity during extreme rainfall for an estimated additional cost of $100,000 which was seen as a worthwhile investment to reduce future risk of damage.


The climate risk assessment of the roof project also identified a role for the new roof in mitigating the impact of rising average temperatures on the centre. Maintaining comfort conditions and avoiding increases in costs for electricity and equipment for air-conditioning will be challenged by increasing average and highest temperatures. Climate modelling indicated the possibility of an increased number of days exceeding 30 degrees Celsius from under 30 per year to nearly 60 per year in the area by 2070. Selecting suitable roof insulation for these future events as part of the roof replacement will help to mitigate these impacts in the future. The centre’s future air conditioning plant will also be designed with these considerations in mind.


The roof structure is also being upgraded to hold a large scale solar photovoltaic (PV) array, as part of the roof replacement project. The solar PV array will contribute to Highpoint’s carbon neutral plans and lower its ongoing energy costs.


“The climate risk assessment of the roof project also identified a role for the new roof in mitigating the impact of rising average temperatures on the centre.” - Nat Roberts, Portfolio Manager, GPT Wholesale Shopping Centre Fund.


The findings from the climate risks assessment informed the proposed roof and hydraulics design scope to ensure the asset’s resilience for the longer term whilst also reducing the immediate operational costs. This is a tangible example of how climate risk assessments and adaptation planning now informs all major investment and development decisions at GPT.