Armed with contemporary knowledge about climate change, housing projects are popping up around the globe that address the construction industry’s strain on the environment and help contribute to the IPCC’s challenging aim of net-zero carbon emissions by 2050.
Three case studies – urban development projects in Milan, York and Hamilton – are typical of developments that are cutting edge, filling the demand for sustainable social housing, providing homes in fast growth areas and meeting the requirements of new building standards ahead of when they are due to come into force.
York, UK
Like in Aotearoa, the energy efficiency of UK housing is poor, contributing significantly to carbon emissions and leaving 13% of households living in fuel poverty.
Changes coming into force in 2025 with the Future Homes Standard aim to reduce carbon emissions by 75–80% in new builds with sustainable technologies and design and upgraded building skills.
The planned new building standards mean that homes will not need costly retrofitting in the future. City of York Council is ahead of the changes, launching a bold scheme to deliver 400 zero-carbon-in-use homes – properties that can be warmed and supplied with electricity and hot water without generating carbon emissions.
The head building contractor on the project, Caddick Construction, says the council is extremely forward-thinking in its approach. While green technology and new building methods have ‘come on in leaps and bounds in recent years, we are yet to see these practices adopted wholesale in the UK housing market’.
Built to Passivhaus standards
Located on the site of a former Nestlé factory, the homes in York are being built to Passivhaus certification, reducing heat loss. Air-source heat pumps will be used for heating and hot water, and roof-mounted solar panels will supply electricity. The council has also considered embodied carbon in the design.
An average new-build home emits around 1.5 t of CO₂ so the annual carbon savings from energy use for all 400 new Passivhaus homes will be 600 t, and a forecast 120,000 kg of CO₂e was saved by changing the foundation design.
Innovation and upskilling
The Passivhaus homes are built using premade timber frames, reducing contractor risk. The council originally added 3-storey dormers to some houses for design reasons, but this altered the thermal envelope and required significantly more insulation.
Building climate-friendly homes puts demands on builders to acquire new skills.
An important aspect of the York project was to incorporate skills development into the procurement process.
City of York Council set out minimum requirements for supporting skills and apprenticeships, and contractors were asked to support the local college in teaching green skills. Contractors were also involved in the design of local college courses on Passivhaus.
Higher costs a challenge
The Passivhaus homes were more expensive to build than standard homes. As the City of York Council started from scratch on the project, the initial sites required considerable time and effort to design and the fees were higher than previous new-build schemes, adding 3% to build costs.
The Passivhaus standard adds around 10–15% to the basic build cost of a property while the use of timber frames added cost pressures due to price inflation.
The council found solutions such as sticking to simpler building forms to reduce insulation and making some homes smaller to help cut costs.
The cost difference to meet Passivhaus standards is also narrowing, while utility bills for residents will be lower and future retrofitting won’t be necessary. However, the higher initial cost is still a challenge for other councils wishing to ensure a high proportion of affordable housing.
Solutions lie with government
The council says further government regulation is needed to set higher built standards so there is consistency and all housing is built to be net-zero carbon.
This would reduce risk pricing by contractors and the higher building costs that make it difficult to compete for new land on the market as other developers with lower build costs can offer higher prices.
Milan, Italy
Around 10% of property in Italy’s financial capital Milan is traditional public housing – twice the average of Italian cities. The strain on the city has been growing with house prices and rents ballooning by more than 40% since 2015 and the demand for affordable housing increasing.
A first for Italy
To help meet the need, Italy’s largest net-zero social housing project has been earmarked for Milan. Called Innesto, it will include 400 apartments and 300 housing units set in 4 hectares.
The winner of a global contest seeking innovative carbon-free and resilient design solutions for regenerating underused urban space, Innesto will be built on the site of a former railway terminal and will embed circular economy principles from its inception.
This includes how it is funded and its design, which will enable the homes to be dismantled for full recycling at the end of their lives.
Carbon neutrality
Innesto will aim for operational carbon neutrality after 30 years, meaning that any carbon the project releases will be balanced by an equivalent amount being removed. This will be achieved with the site’s innovative heating network, which will be powered by urban wastewater, as well as the recyclable prefabricated construction.
Hamilton, Aotearoa
As populations grow, so does the demand for housing. That’s the case with Hamilton Kirikiriroa, where Peacocke, a new suburb being constructed on a greenfield site on the south side of the Waikato River, will comprise 7,400 new homes housing up to 20,000. A range of housing types will be accommodated, including medium-density and high-density housing.
Climate ready
The beauty of building a new suburb from scratch is that the latest technology and advances in urban design can be incorporated. Peacocke will be Kirikiriroa’s biggest ever investment in the environment – established as a climate-ready neighbourhood that protects the natural surroundings and giving residents travel options such as wider footpaths, separated cycleways and public transport.
Greenfield areas offer great community outcomes from the start, says Sonia Baker, Green Growth Programme Manager at Hamilton City Council (HCC). ‘Resilience has been, and continues to be, a key consideration for urban development of Peacocke. This has been reflected in the development of infrastructure that will support new housing in the area.’
HCC has a catchment management plan to achieve no net loss of terrestrial, wetland and stream biodiversity. To deal with potential climate-related heavy rains, stormwater pipes will be installed and natural solutions to water management provided in the form of 30 wetlands and stormwater ponds to ensure community resilience.
Peacocke will represent best practice in urban design and ecological outcomes as a planned, resilient community enhancing the natural environment while providing for higher-density housing near the central city.
‘Higher-density neighbourhoods will be supported by transport options that are reliable, efficient and high quality,’ says Sonia. ‘Close proximity to the central city helps to reduce emissions by making it easier for residents to walk and bike.’
Bat protection
Requirements for houses in the development include 50 m buffer zones along the Waikato River, gullies and known bat roost sites and identifying areas where bats might fly from one habitat to another – protecting against light and other impacts of housing.
These ecological corridors will give future residents the feeling that they are living in an urban forest.
Green Star rating
Peacocke is registered for a New Zealand Green Building Council Green Star – Communities rating. The development is being assessed across a range of criteria around the quality of the suburb’s sustainability and as a healthy place to live.