Energy use in buildings represents a large share of total energy use; therefore, the energy efficiency of ventilation systems is of key importance for reducing energy losses and achieving climate targets. The thesis examines the energy efficiency of a commercial ventilation unit with heat and moisture recovery (recuperation), equipped with an enthalpy heat exchanger, under real operating conditions. In the experimental part, one-minute measurements of temperature, relative humidity and pressure were performed at four characteristic points of the ventilation system (outdoor air, extract air, supply air and exhaust air) at four ventilation levels (54, 126, 180 and 234 m³/h). Based on the measured values, psychrometric quantities were calculated, as well as the sensible, latent and total enthalpy efficiency of the unit, together with an analysis of measurement uncertainty. The results showed that the sensible efficiency decreases with increasing flow rate, from 88% at the lowest to 80% at the highest level, while the latent efficiency ranges between 54% and 70%. The total enthalpy efficiency amounts to between 76% and 84%. The measurement uncertainty of the latent efficiency was relatively high due to the small humidity potential. The measured values of sensible efficiency are comparable with the manufacturer's data.
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