Aotearoa’s housing stock is ageing and many existing buildings use outdated energy systems that are inefficient and contribute to climate change or are susceptible to climate change impacts. Carbon-neutral retrofitting is a viable way of adapting buildings to climate change without exacerbating climate change impacts, but there are challenges.
Carbon-neutral building retrofit technologies
Conventional retrofitting options aim to minimise operating energy. Carbon-neutral retrofitting options consider whole life cycle energy, including the impact of embodied carbon.
Carbon-neutral building technologies aim to reduce operational energy consumption and carbon emissions by incorporating a range of aspects such as renewable energy sources, building design features, energy system improvements and energy storage solutions:
- Renewable energy systems use renewable sources like solar, biomass and wind to produce heat and electricity for buildings. They include technologies such as solar panels, heat pumps and wind turbines. Solar systems are versatile for various climates, while heat pumps and wind turbines depend on specific regional and climatic conditions.
- Passive design strategies, also known as building design features, focus on reducing energy needs by improving daylight, ventilation and insulation. Examples include window glazing, shading and green roofs, which help reduce energy use across different climates.
- Energy efficiency in heating, ventilation and air conditioning (HVAC) systems is critical as they account for a significant portion of building energy use.
- Energy storage systems such as thermal storage and batteries help balance energy supply and demand. Batteries support renewable energy systems by addressing power fluctuations.
Implementing carbon-neutral retrofit technologies also presents challenges such as high upfront costs, limited installation space and the complexity of calculations and decision making.
Optimisation techniques and generative design
Incorporating climate change effects into life cycle assessments of retrofit design is essential to ensure that retrofitting solutions remain effective in the future. Comprehensive evaluation indicators are needed to ensure the effectiveness and sustainability of retrofit designs, particularly as extreme weather events and temperature fluctuations become more common in the long term.
Achieving optimal results with carbon-neutral retrofit design is challenging as three key factors must be balanced: environmental impact, energy efficiency and cost of investment and operation. It is difficult to find a solution that achieves an acceptable level for all these factors. Optimisation techniques are an efficient way of selecting the most effective retrofitting solutions. These strategies consider the long-term costs, future energy efficiency and carbon emissions associated with different retrofitting options.
Generative design, unlike traditional design, focuses on setting procedural rules, constraints and flows to automate the design process and achieve optimal design solutions. Generative design is especially practical for achieving contractional objectives and complex decision making in design. When optimising building retrofits to achieve climate change goals, careful consideration of several factors is needed:
- Future weather projection and energy demand prediction – projections of weather parameters such as temperature, cloud cover, wind speed and humidity, which significantly influence building energy demand, using climate change models and incorporating those projections into prediction models of future energy consumption.
- Energy performance improvement and prediction of renewable energy production – measures such as improved insulation, passive strategies and HVAC upgrades combined with energy and thermodynamic modelling enable efficient retrofit design.
- Life cycle optimisation for retrofitting – using optimisation techniques to minimise the lifetime cost of retrofitting
(investment and operation costs), minimising environmental impacts and embodied energy and maximising energy efficiency.
Generative design and optimisation techniques have the potential to transform carbon-neutral building retrofitting processes by ensuring that retrofit designs are not only functional but also resilient and cost-effective in the long term.
Future research prospects
The predicted long-term consequences of climate change create a need for mitigation and adaptation actions. Carbon-neutral retrofits that combine adaptation and mitigation retrofit design foster synergies between the two strategies. Carbon-neutral retrofits play a crucial role in this process by minimising energy consumption and greenhouse gas emissions while simultaneously enhancing a building’s resilience to climate-induced stressors.
However, despite the proven benefits of climate-resilient retrofit options, there are significant challenges in the implementation of climate-resilient carbon-neutral retrofits. This is because prediction thermal models are complex, computationally heavy and difficult to apply in real-world design practices.
Regardless of the potential benefits of carbon-neutral retrofit solutions, there is a huge gap in evaluating the effectiveness of the measures in terms of cost feasibility, environmental impacts and energy efficiency outcomes. To unlock the potential of these solutions and bridge this gap, systematic evaluations and robust data analysis are essential to enhance decision making and ensure that design meets retrofit goals while balancing cost, environmental impact and energy efficiency.