EPBD and Indoor Air Quality

Indoor air quality is the air occupants actually breathe, shaped by ventilation, by pollutants from cooking, cleaning, furnishings and outdoor air, by moisture and mould, and by temperature and humidity. The EPBD recast gives indoor environmental quality, including air quality, more explicit attention than earlier versions, recognising that energy renovation that tightens a building without ensuring adequate ventilation can worsen the air its occupants breathe. That recognition matters because it reframes renovation: energy improvement and air quality are joint aims, not competing ones, and a project that improves one while harming the other has not succeeded.

Pollutant sources in homes are varied and ordinary. Cooking produces particles and nitrogen dioxide, particularly with gas cooking. Cleaning products, furnishings and building materials emit volatile compounds. Outdoor air brings traffic pollution and pollen indoors, particularly where ventilation is uncontrolled. Occupants themselves produce carbon dioxide and moisture. Ventilation removes or dilutes those pollutants, filtration can reduce some outdoor pollutants, and source control, such as cooker hoods that extract outdoors and low-emission materials, reduces them at origin. A good indoor air strategy uses all three approaches, not ventilation alone.

Moisture links air quality to building health. Inadequate ventilation in a tightened home allows humidity to rise, condensation to form on cold surfaces, and mould to grow, with consequences for both fabric and occupants. Energy measures that reduce air leakage therefore increase the importance of purpose-provided ventilation, and a renovation model that shows only energy, without a ventilation and moisture note, is incomplete. Moisture risk should be assessed for vulnerable rooms and details, particularly bathrooms, kitchens and cold corners, before tightening work is specified.

Measurement can help, but it needs interpretation. Carbon dioxide levels indicate ventilation adequacy in occupied rooms, humidity indicates moisture risk, and particle sensors indicate cooking and outdoor pollution, but no single sensor gives a complete air quality picture, and sensor placement and calibration affect readings. A short monitoring period in mild weather, or in an unoccupied home, says little about winter occupied conditions. Monitoring is a diagnostic aid, not a verdict, and it should be interpreted alongside ventilation design and occupant behaviour.

Before renovating, assess the building's current ventilation, moisture history and pollutant sources. Note how fresh air currently enters, whether extract fans work and are used, whether windows are opened for purge ventilation, and whether damp or mould has occurred. Then design energy measures with ventilation: ensure purpose-provided ventilation where infiltration will fall, provide boost extraction in wet rooms, and consider filtration where outdoor pollution is high. That joint design prevents the common failure of an energy-efficient but stuffy home.

For non-residential buildings, indoor air quality also involves occupancy density, system maintenance and commissioning. Schools, offices and health buildings with high occupancy need ventilation designed for peak occupancy, not average occupancy, and systems that are not maintained or commissioned will underdeliver even where design rates look adequate. Regular maintenance, filter changes and controls checks are part of air quality, not optional extras.

By place, indoor air quality requirements and guidance vary. Some member states have explicit indoor air quality or ventilation requirements in building codes, with rates and system expectations, while others address air quality through general health and building guidance. Climate matters too: warm southern buildings face overheating and ventilation-for-cooling questions that cold northern buildings face less, while northern buildings face winter ventilation and moisture questions more acutely. National guidance for the country concerned should be followed.

For UK readers, indoor air quality and ventilation follow UK building regulations and guidance, not the EPBD, although the joint energy and air quality principle is the same. A UK renovation should be designed with ventilation and moisture in mind, under UK rules, just as an EU renovation should under national EPBD implementation.

A common mistake is to draught-proof, insulate and replace windows without a ventilation plan, and then to discover condensation, mould or stuffiness that a joint design would have prevented. Another mistake is to treat air quality as solved by a single device, such as an air purifier, when ventilation, source control and moisture management are all needed.

A further mistake is to rely on a single sensor reading, or on a feeling of freshness, as proof of good air quality. Air quality varies by room, season and activity, and a single reading in one room on one day cannot represent a building's air quality overall.

Keep the ventilation design, moisture notes, monitoring records where available, and maintenance records together with the energy model. That file supports healthy renovation and future troubleshooting.

Questions to ask include: how will this renovation affect ventilation and moisture, what boost provision exists for wet rooms, and how will ventilation be maintained. Those questions keep air quality in renovation where it belongs.