That contradiction is what our new study in Construction Innovation set out to explain. Energy efficiency, water efficiency and indoor environmental quality are usually managed as three separate checklists, often by three separate consultants, signed off at three separate stages. They are one coupled system, and both the real gains and the real failures live in the coupling.
Every litre of water a building moves, heats and treats carries an energy cost. An airtight envelope that saves heating energy will, without adequate ventilation, turn moisture into mould and degrade the air people breathe. A lighting retrofit changes heat gains, which changes cooling loads, which changes how windows are used. Treated in sequence, each upgrade quietly taxes the next. Treated as one system, the gains compound.
We worked with producers, policymakers, investors, academics and occupants, and read the evidence through a multi level perspective on socio technical transitions. The signal was consistent across groups: performance is lost not in the technology but in the seams between disciplines, contracts and stages of a project. Nobody owns the interaction, so nobody designs for it.
New Zealand is close to an ideal proving ground for doing better. Its grid is largely renewable, smart metering is widespread and the country has committed to a net zero pathway. Those conditions make it possible to measure integrated performance in occupied buildings rather than estimate it at consent. As Europe moves to mandatory whole life carbon accounting, integrated building performance is becoming a global baseline rather than a niche ambition.
The practical implication is about procurement as much as engineering. Clients can ask for a single integrated performance brief instead of three separate targets; regulators can test the interaction between energy, water and air quality rather than each in isolation; and universities can train engineers and architects to design the seams. Our School is opening this work to international partners, because the problem is shared and the evidence base is still thin.
The work behind it
Poorisat, T., Aigwi, I. E., Doan, D. T., and GhaffarianHoseini, A. (2026). Integrating energy efficiency, water efficiency and indoor environmental quality towards advancing sustainable building designs and practices in New Zealand: Stakeholders’ perspectives. Construction Innovation, 26(9), 79 to 114.
The study gathered the views of producers, policymakers, investors, academics and occupants, and analysed them through a multi level perspective on socio technical transitions, which treats change as the interaction of niche innovation, established regimes and wider pressures.