INDOOR AIR QUALITY · 25 SEPTEMBER 2026

Fresh air has an energy cost.
How do we manage both?

Ventilation is essential. But every cubic metre of outdoor air brought into a building can also bring a heating or cooling load with it.

THE PROBLEM

We sometimes treat air quality and energy efficiency as separate jobs.

They are not. A building needs enough outdoor air to manage moisture, odours and indoor contaminants, but the outside air arrives at the temperature and humidity the weather gives us. The building then has to condition it.

EECA notes that mechanical ventilation can help keep air fresh and moisture-free, and that heat-recovery systems can recover heat from outgoing air before fresh air enters the building.

THE BETTER QUESTIONHow much ventilation does the building need right now — and how can we deliver it efficiently?

New Zealand still has a moisture problem.

BRANZ's HEEP2 research published in August 2026 found visible mould in 48% of owner-occupied homes, 32% reporting dampness, and 75% experiencing condensation during winter. BRANZ says the result is a reminder that ventilation, heating and overall building performance need to work together.

That does not mean “more ventilation” is automatically the answer. The design question is broader: where is moisture being generated, where is air moving, what temperatures are surfaces reaching, how much outdoor air is required, and what energy is being spent conditioning that air?

REFRAME

Ventilation should be part of the energy model.

Air quality, humidity, temperature and energy use influence each other. A useful system understands those relationships instead of optimising a fan in isolation.

SenseCO₂, temperature, humidity and relevant air-quality conditions.

DecideWork out how much outdoor air is actually useful.

RecoverLook for heat or energy that would otherwise be lost.

AdaptChange operation as occupancy and conditions change.

WHERE ELSE CAN WE USE IT?

The principle extends beyond houses.

Commercial buildings

Occupancy, schedules and indoor conditions can change significantly through the day.

High-moisture spaces

Bathrooms, kitchens and specialised environments can need targeted extraction and control.

Energy-aware ventilation

Ventilation can become part of a wider strategy involving heating, cooling, recovery and storage.

EVOLUTIONFX TAKE

Healthy air and low energy use should not be opposing goals.

The challenge is to design the system around what the building actually needs, then recover or avoid energy where the design allows.

Explore indoor air quality technology →

RESEARCH & FURTHER READING

EECA · Reduce dampness and improve airflow
BRANZ · What mould reveals about building performance

Fresh air has an energy cost.How do we manage both?