Air Quality, what is the applicable state regulation?

The origin of much of the contaminated air inside enclosed spaces is due to the metabolic activity (breathing and perspiration) of individuals. This metabolic activity must be combined with the routine tasks performed in different locations (such as cooking, for example) and the pollutants emitted by the building materials themselves. Therefore, good indoor air quality in our buildings will depend on the ventilation provided, which is capable of extracting contaminated air from the interior and supplying clean air from the outside. Only sufficient and efficient ventilation will be able to dilute the indoor air pollutants and provide an acceptable air quality that does not endanger human health.

Air Quality and Current Regulations

Current regulations ensure that indoor air quality is maintained within acceptable limits, depending on the use of each of the enclosed spaces. Thus, the regulations not only dictate a specific flow of air but also take into account numerous factors (total pollution load depending on building materials, activities performed, occupancy…) to prescribe the indoor air quality that must be guaranteed in a given location.

State Regulations

In Spain, the requirements for indoor air quality in residential buildings (single-family or multi-family) or in parking lots and garages of buildings for any other use are dictated by the Technical Code of Building (CTE DB HS 3). The applicable regulations for other buildings will be UNE-EN 13779. Ventilation of non-residential buildings. Performance requirements for ventilation and conditioning systems.

RITE

According to RITE 2013, five different methods can be used to determine the minimum ventilation flow rate that provides the required indoor air quality (IDA):

• Based on certain metabolic activity: “Indirect method of outdoor air flow per person”.

• According to the olfactory perception of the occupants: “Direct method by perceived air quality”.

• In cases where metabolic activity is high: “Direct method by CO2 concentration”.

• When occupancy is intermittent: “Indirect method of air flow per unit of area”.

• If there are specific contaminants present in the air: “Dilution method”.

As noted in the regulation, the requirements for indoor air quality in hospital and clinical buildings are dictated by the UNE 100713. Air conditioning installations in hospitals.

What Does the Technical Code Cover?

As previously mentioned, the indoor air quality for homes is established in CTE DB HS 3, Indoor Air Quality. The Technical Code, in its new version from 2017, states that in the habitable spaces of homes, an exterior air flow must be supplied to dilute the annual average concentration of carbon dioxide, so that it is below 900 ppm. Since this air flow must also serve to dilute the pollutants not emitted by individuals, a minimum flow rate of 1.5 l/s per habitable space is set when they are not occupied.

Minimum Flow Rates for Constant Flow Ventilation Systems

The document establishes the following minimum flow rates for habitable spaces:

• Main room: 8 l/s, regardless of the number of rooms in the home.

• Other rooms: 4 l/s.

• Living rooms and dining rooms, or other spaces with similar use, such as offices or game rooms: if the house has 0 or 1 room, 6 l/s; if it has 2 rooms, 8 l/s; if it has 3 or more, 10 l/s.

• In wet spaces (with the modification of CTE HS 3, no distinction is made between kitchens, bathrooms, toilets, laundry rooms…) two types of flow rates are established (minimum total and minimum per space). For homes with 0 or 1 room, the total minimum is 12 l/s and the minimum per space is 6 l/s. In homes with 2 rooms, the total minimum is 24 l/s and the minimum per space is 7 l/s. For homes with 3 or more rooms, the total minimum is 33 l/s and the minimum per space is 8 l/s.

Other Aspects to Consider:

If two uses coexist in the same space, the one requiring a higher flow must be considered. If there is both a wet and a dry area in the same space, each must be supplied with its corresponding ventilation flow rate (supply or extraction).