Definition
The U-value is the rate of heat transfer through a building element per square metre per degree of temperature difference, in W/m2.K. A low-U wall or window loses little heat; a high-U one loses a lot.
U-value vs the exchanger k-value
Do not confuse them. The exchanger overall conductance (UxA in the epsilon-NTU method) describes the recovery core; the building U-value describes the envelope. They meet at the load calculation: better envelope (lower U) means less heating demand, which both cuts energy and changes how much recovery is worth recovering.
Why recovery still matters with a good envelope
Even a Passive House with very low U-value still ventilates (see Passive House recovery), and that ventilation air is the dominant remaining load. Decarbonisation strategies pair a tight envelope with high-effectiveness recovery so the ventilation load – not the walls – is what gets addressed.
Frequently asked questions
Does better insulation remove the need for recovery? No – it shifts the largest load to ventilation air, which only recovery addresses.
Is lower U always better? Up to a point; beyond code, the marginal cost often beats the marginal energy saving.
Need help specifying the right air-to-air heat recovery for your project? Contact the QIYU engineering team – WhatsApp +86 157 5335 5505, or email kuns913@gmail.com.
Questions fréquemment posées
What is U-value?
U-value is the rate of heat transfer through a building element per square metre per degree of temperature difference, in W per m2 per K; lower means better insulation.
How does recovery relate to U-value?
Recovery reduces the ventilation load that the building envelope U-value would otherwise have to compensate for; together they set the total heating and cooling demand.
Questions fréquemment posées
What is U-value?
U-value is the rate of heat transfer through a building element per square metre per degree of temperature difference, in W per m2 per K; lower means better insulation.
How does recovery relate to U-value?
Recovery reduces the ventilation load that the building envelope U-value would otherwise have to compensate for; together they set the total heating and cooling demand.
Spécifiez le bon échangeur
Nos ingénieurs dimensionnent le noyau selon votre débit, température et budget de perte de charge, et choisissent la récupération par plaque, rotative ou caloduc selon l'application. Lisez le guide de l'échangeur , ou contactez-nous pour une spécification.
Produits connexes
Récupération par plaque, rotative ou caloduc pour le CVC et la ventilation.
Noyaux stationnaires à grande surface pour l'air et le liquide.
Récupération d'énergie à haute efficacité pour grands débits.
Courants passifs et totalement séparés pour applications propres.