Comparision Between Air Changes Per Person's Extract Ventilation Rate

Ventilation rates are often expressed as a volume rate per person (L/s per person). The conversion between air changes per hour and ventilation rate per person. The equation to calculate this is L/s = (ACH*D*h)/60 Where L/s is the ventilation rate per person (L/s per person), ACH is the air changes per hour, D is the Occupant density (occupants per square foot, occupants per square meter) h is the ceiling height (ft. meters)

As per Building Regulations 2010, Approved Document F, every kitchen, bathroom, utility room and sanitary accommodation requires an extract ventilation due to the high moisture level in these rooms and to achieve the required and appropriate ventilation rate. The extracts can be intermittent or continuously operating.
The below table shows the whole dwelling ventilation rate as required by Building Regulations. The below information is based on two occupants in the main bedroom and single occupant in all other bedroom, an extra 4 l/s to be added per occupant if a higher level of occupancy is expected.
Table 1.3 whole Dwelling ventilation Number of bedrooms in dwelling 1 2 3 4
Whole Dwelling ventilation rate (l/s)
13
17
21
25

It further requires that the minimum ventilation rate should be not less than 0.3 l/s per m2 the of internal floor area. (This includes all floors, e.g. for a two-storey building add the ground and first floor
Internal wall partitions blocking air passage.
As previously mentioned mechanical ventilation controls the amount of air allowed into the building by allowing the installer to set the correct level airflow as required by Building regulations. In which case, the introduction of mechanical ventilation becomes very necessary to achieve the desired air flow where natural ventilation is reduced or gets restricted to the reasons mentioned above.
Looking back into the MVHR, the units are designed to provide continuous supply of fresh air to provide good indoor quality air and eliminating high moisture level, it also comes with summer bypass system which means that during summer periods the intake air will not be will not be heated up when it comes into the heat exchange unit. This can help in maintaining comfortable indoor temperature. MVHR units helps save on energy bills as it retains heat for thermal comfort .Low and easy maintenance as they have easy accessible filters. They are easy to install. They operate on extremely low level of noise. Highly efficient with low running costs. MVHR are easy to be