EPBD guidance documents published by European Commission: IEQ parameters and ZEB energy calculations

On 30 June 2025, the Commission adopted a support package offering practical guidance to help EU countries implementing and transposing the Energy Performance of Buildings Directive into national law by 29 May 2026. This package consists of 13 guidance documents dedicated to specific topics, all available from EPBD main webpage[1]. In the following we look on two most technical documents which are supported also with REHVA recent documents. These cover relevant Indoor Environmental Quality (IEQ) parameters and Zero Emission Building (ZEB) requirements calculations, the topics where REHVA Technical Guidance for EPBD Implementation Task Force has intensively worked during last years.

New provisions for indoor environmental quality (IEQ) and their possible implementation options are explained in the EPBD guidance document: Technical building systems, indoor environmental quality and inspections (Articles 13, 23 and 24)[2]. As there is new definition in EPBD for IEQ according to which a minimum scope of IEQ addresses thermal comfort and ventilation/indoor air quality domains, the guidance document provides a comprehensive table of relevant IEQ parameters when setting design requirements (e.g. in line with Articles 7(6) and 8(3)), conducting commissioning, performing monitoring (e.g. in line with Article 13(5)), and conducting inspections (in line with Article 23), Table 1. Next table in the guidance document provides recommended ranges for IEQ parameters for new buildings based on a medium expectation of occupants that corresponds to EN 16798-1 Category II values. As whole the document provides about 10 pages overview explaining how IEQ can be controlled at design, commissioning, monitoring and inspection stages and which parameters are feasible to be measured directly, and which ones can be assessed indirectly. To go further from this guidance document explaining principles of IEQ, REHVA has developed a model regulatory text to support harmonized implementation of EPBD IEQ provisions. This REHVA document provides an example on how EPBD IEQ provisions can be addressed in the regulation and relevant requirements set with measurable indicators[3]. Together with European Commission guidance document a model regulatory text should serve as a practical example of evidence based IEQ useful minimum implementation.

Table 1. Relevant parameters for Indoor Environmental Quality as proposed in EPBD guidance.

D = Design, C = Commissioning, M = Monitoring, I = Inspection

a) In assessing indoor values, consideration of outdoor values for air temperature, humidity, CO2 and PM2.5 as well as of other outdoor pollutant levels such as CO, NO2 is necessary. Further indicators may be monitored or inspected in order to validate IEQ management performance.

b) Khovalyg, D., et al., 2020. Critical review of standards for indoor thermal environment and air quality. Energy and Buildings, 213, p.109819.

c) For non-residential buildings filters are specified in EN 16798-3

d) PM2.5 continuous monitoring may only be needed if the outdoor PM2.5 pollution levels are above those set in EN 16798-1 guidelines. If above, particulate matter should be controlled with filters in the ventilation system and infiltration through building envelope should be checked. Indoor pollution levels may also need to be considered (e.g., for residential buildings, in case of local space heaters with indoor emissions).

e) Volatile Organic Compounds (VOC) refer to a variety of chemicals that can originate in a building, e.g. from building materials and furniture. They are not included here as an indicator, as newer requirements are more focused on specific indicators such as formaldehyde, benzene, etc.

f) Where relevant, based on national, regional, or local health protection priorities or on specific identified issues which should be considered in the design and operation of the building. For example, nitrogen dioxide and carbon monoxide would be relevant when designing indoor parking areas, or if the building is located in polluted areas or in case of indoor pollution sources. Where relevant, e.g. in the case of specific issues such as indoor problems caused by combustion devices, measurement could be needed to address these specific pollutants. A map of the indoor Radon concentration is provided by the Joint Research Centre of the European Commission (http://data.europa.eu/89h/jrc-eanr-02_indoor-radon-concentration).

g) Optional element of IEQ definition: it is recommended that it is at least addressed in the design of new buildings.

h) Illuminating engineering society, IES LM-83-12, 2012.

i) World Health Organisation (WHO). Guidelines for community noise, 1999.

Zero Emission Buildings thresholds and other indicators calculation is explained in another European Commission guidance document: Zero Emission Buildings (Articles 7 and 11)[4]. This document explains the calculation principles of ZEB energy demand (total primary energy) threshold, operational greenhouse gases threshold and total primary energy covering requirement. It is shown that EPBD includes a flexibility to calculate these indicators with two possible assessment boundaries, either with building assessment boundary or alternatively with building site assessment boundary. If the building assessment boundary of EN ISO 52000-1 is used, additional multipliers for on-site renewable energy generation and ambient heat captured by heat pump are applied with a reference to REHVA Primary Energy and Operational CO2 calculation guidance document[5]. In this fashion, calculation examples provided with two assessment boundaries provide the same results. To have an idea of ZEB calculations, an example from the EPBD guidance document is reproduced in Figure 1 and Table 2.

Figure 1. Calculation example of ZEB multifamily apartment building used in the EPBD guidance document showing two possible options for the assessment boundary.

Total primary energy calculations conducted in Table 2 show how zero multipliers are applied for the rooftop PV and ambient heat in Case 1. There is also a flexibility in EPBD to reduce PV electricity used on-site for non-EPB uses with recommended PEF=1.0. Another flexibility is to take exported PV electricity to grid into account or not to take. If considered, PEF=0.9 is recommended. It can be seen that in Case 1 and 2 total primary energy result is 16.7 kWh/(m2.y). Total primary energy covering on annual bases is coming from rooftop PV, ambient heat, and renewable and nuclear fractions of the grid electricity resulting in 53.6 kWh/(m2.y). Therefore, the total primary energy covering requirement is fulfilled as 53.6 > 16.7.

Table 2. Calculation example from European Commission EPBD guidance document: Total primary energy use of the building and compensation of the non-compliant energy from the grid by the renewable energy produced on-site and either exported to the grid or used on-site for non-EPB uses.

Examples provided in the guidance document explain in detail calculation principles for the total primary energy threshold, operational greenhouse gas emissions and for the requirement to cover total primary energy use from Art 11 a) - d) options. This should ensure that everybody will get the same result.

There is an issue with total primary energy factors which can lead to some problems with district heating. It should be noted that total PEF cannot recognise the benefits of district heating and cooling, and the positive influence of renewable energy. A classic example of a heat pump in a building or in a district heating plant should lead to the same energy performance if the efficiency is the same and there are no network losses, but this is not the case if total primary energy factors, which cannot be by the definition smaller than one, are used. This problem can be tackled by using EPBD flexibility allowing to use weighting factors instead of total PEF. Possible solution is to replace total primary energy factor of district heating with relevant weighting factor and still to use total primary energy factor for grid electricity to ensure equal treatment of district heating and heat pumps.