HVAC stands for heating, ventilation and air conditioning. The most important of them in this very draughtproof house is ventilation.
At the heart of the mechanical ventilation and heat recovery (MVHR) system in this house is a counterflow air-to-air heat exchanger. It recovers heat from the stale outgoing air to preheat the fresh incoming air.
It is made of reclaimed glass tubes. They were first used for heat recovery in a Suffolk maltings in the 1980s.
Glass tube heat exchanger under construction.
The MVHR system is designed to consume 90% less electricity than normal. It should ventilate the house using 60-70% less electricity than so-called ‘good or best practice’, which is typified by Passivhaus-certified MVHR systems.
Given that a ‘standard’ MVHR system may consume ‘only’ 100-120 watts, saving some of this power may sound trivial. But the system in this house will reduce CO2 emissions by half a tonne per year compared to the usual European MVHR system.
Multiple services under construction in the corner of the kitchen. Visible are highly-insulated hot and cold water pipes and a circular galvanised ventilation duct.