Model Indoor Environmental Quality regulation to fulfil new provisions of 2024 EPBD recast

– Common proposal by Nordic Ventilation Group, REHVA and EUROVENT association

The full text of the policy paper can be found at: https://www.rehva.eu/fileadmin/user_upload/2024/IEQ_Guidance_2025.pdf

To help to implement new IEQ provisions in national regulation, REHVA and Nordic Ventilation Group experts have developed a model IEQ regulatory text. It aims to support national regulators who can get an idea, how EPBD complaint regulation could look. Evidently there are different national practices, but all Member States need to check the development needs of existing regulations against revised EPBD.

EPBD has introduced new provisions for indoor environmental quality (IEQ) which implementation in national regulations may require considerable effort. These new provisions include:

·         A new definition for IEQ in Article 2(66) according to which a minimum scope of IEQ addresses thermal comfort and ventilation/indoor air quality domains.

·         EPBD introduced new principle of optimal indoor environmental quality. When setting minimum energy performance requirements, Article 5 states that “those requirements shall take account of optimal indoor environmental quality, in order to avoid possible negative effects such as inadequate ventilation…”. Revised Articles 7 and 8 for new and existing buildings stress IEQ for both new buildings and major renovations by stating that the issues of optimal indoor environmental quality shall be addressed.

·         Article 13 calls to establish national IEQ requirements: “Member States shall set requirements for the implementation of adequate indoor environmental quality standards in buildings in order to maintain a healthy indoor climate.” These requirements may be referred when recommendations to improve IEQ are provided in EPC-s which is new provision in Article 19(5).

·         Article 13 also requires to equip new non-residential ZEBs with IAQ monitoring and regulation devices.

·         Article 19 requires that the energy performance certificates include recommendations for the improvement of IEQ.

The following model regulatory text has been developed from EPBD provisions and by setting requirements with measurable indicators based on to those of the Level(s) framework for sustainable buildings [1]. Proposed text is expected to serve as an example of evidence based IEQ useful minimum implementation to support harmonised national EPBD implementation. All numeric values included serve as examples, following the Commission guidance [2] recommendation to use Category II specified in EN 16798-1:2019 (medium occupant expectation), whose values ensure avoiding adverse health effects and comfort and well-being of occupants.

In the following the regulatory text proposal is published with couple of examples from explanatory report, the full document can be found from REHVA website.

Model Indoor Environmental Quality regulation

1. Subject matter

1.1 This model regulation specifies minimum requirements for thermal comfort, indoor air quality (IAQ) and noise from building services compliant with 2024 EPBD for new buildings and major renovations with necessary considerations for residential and non-residential buildings.

1.2 Requirements apply for design and operation of buildings, including monitoring and long term assessment of indoor conditions.

1.3 Commissioning of technical buildings systems which includes test procedures and measurement methods to hand over, and regular inspection of heating, ventilation and air conditioning systems are not included in this document.

1.4 Indoor environmental quality (IEQ) requirements follow the EPBD minimum scope that is limited to thermal comfort and IAQ. Lighting and acoustics, other than the noise of building services, are not included in this document.

2. Definitions

2.1 ‘Indoor environmental quality [3]’ means the result of an assessment of the conditions inside a building that influence the health and wellbeing of its occupants, based upon parameters such as those relating to the temperature, humidity, ventilation rate and presence of contaminants.

3. Design values and requirements for thermal comfort

3.1 In continuously occupied spaces general thermal comfort shall be maintained and local thermal discomfort avoided.

3.2 Room temperature [7]comfort ranges for sedentary activities (1.2 met) specified in Table 1 shall be maintained in the occupied zone [4].

Table 1. Room temperature [5] acceptable comfort ranges in the occupied zone [6].

3.3 The values for dimensioning of the heating system shall be the lower values of the comfort range during heating season (Table 1) and values for dimensioning cooling systems shall be the upper values of the comfort range during cooling season.

3.4 Heating season is defined when the outside running mean temperature is below 10°C and cooling season when it is above 15°C. Between 10°C and 15°C running mean temperature, room temperature may lie in between the lower heating season and the higher cooling season value.

3.5 To avoid local thermal discomfort [7], draught [8], radiant temperature asymmetry, vertical air temperature difference and floor surface temperature shall be taken into account when designing buildings and HVAC systems.

3.6 Long term performance of a building to maintain room temperatures in the range specified in Table 1 during occupancy [9] can be evaluated with dynamic temperature simulations. Temperature simulations are not necessary in the case of heating and cooling systems where temperature control is implemented with room thermostats and heating and cooling powers are sufficient. For other systems and in the case of using building thermal mass as a capacity to react to external signals [10], acceptable deviation from the specified range in Table 1 is maximum 5% of the occupancy time. In residential buildings, 150 Kh (Kelvin hours) above 26°C is an acceptable excess [11].

4. Design values and requirements for indoor air quality

4.1 General

4.1.1 Indoor air quality shall be controlled by source control (pollutant sources), ventilation, and possible filtration of outdoor air.

4.1.2 Source control must be applied for pollution sources from building materials and interior design through the use of low polluting building materials [12], and with the use of local exhausts where relevant.

4.1.3 To maintain an acceptable level of pollutants in the indoor environment, minimum outdoor air ventilation requirements given in 4.2 and 4.3 shall be used to dimension the ventilation system.

4.1.4 To control the entry of outdoor particulate matter, outdoor air filters [13] in the ventilation system may be used. In zones where outdoor air intake without outdoor air filters is used, the particulate matter PM2.5 cannot be higher [14] than 10 µg/m³.

4.2 Ventilation in non-residential buildings

4.2.1 In indoor spaces where the criteria for indoor environments are set by human occupancy and where the production or process does not have a significant impact on the indoor environment, the required outdoor air ventilation rate shall be calculated:

where [15]

qs         design outdoor air ventilation rate, L/s (1 L/s = 3.6 m³/h)

N         design value for the number of persons in the room,

qp        ventilation rate for occupancy per person, 7 L/(s person)

AR        room floor area, m²

qB        ventilation rate for emissions from building, default value 0.7 L/(s m²) assuming low polluting materials. When very low-polluting building materials (certified by national material emission control/labelling systems) are used, qB = 0.35 L/(s m²).

4.2.2 In indoor spaces where are other pollution sources in addition to human occupancy and emissions from building, the sufficiency of ventilation rates provided by Equation 1 shall be checked and ventilation rates increased where relevant.

4.3 Ventilation in residential buildings

4.3.1 In residential buildings the total ventilation of a whole residence shall be at least 0.42 L/(s m²) [16]. Room specific minimum ventilation requirements are given in Table 2.

Table 2. Minimum design airflow rates in residences [17].

1) Transfer air from bedrooms can be used as a part of supply air but 12 L/s is minimum outdoor air rate.

2) Airflow rate in the kitchen when cooker hood is not in operation.

3) Fire regulations are to be followed.

4.3.2 The ventilation supply airflows to the bedrooms and living rooms are expressed in Table 2 as an outdoor airflow rates which shall be supplied primarily to living rooms and bedrooms. The ventilation air for the kitchen, bathroom and toilet has to be transfer air from the bedrooms and living rooms. Doors or specific openings must allow transfer air flows without significant pressure loss. From wet rooms extract airflows shall be used to remove pollutants and humidity.

5. Ventilation system requirements

5.1 General requirements

5.1.1 Ventilation system must be designed so that it enables to fulfil the requirements specified in chapter 4.

5.1.2 Ventilation system shall ensure air movement from rooms with higher air cleanliness to rooms with lower air cleanliness as specified in Table 3.

Table 3. Classification of indoor air cleanliness and ventilation requirements in rooms.

5.1.3 Air intakes shall be located where the outdoor air is less polluted.

5.1.4 Exhaust air shall be discharged from the building so that harmful effects in the building, to the adjacent buildings and to the occupants close to the building will not be caused.

5.1.5 To avoid cross contamination, minimum distances [18] shall be considered to find optimal locations for intake and exhaust openings.

5.2 Operation for optimal indoor air quality in non-residential buildings

5.2.1 Ventilation systems in non-residential buildings shall be controlled according to occupancy. Concentration of CO₂ can be used as a proxy for ventilation to operate ventilation system in between design and minimum ventilation rate.

5.2.2 Minimum ventilation rate shall be calculated with Equation 1 with no occupancy (n=0).

5.2.3 For CO₂ concentration setpoint [19] the total ventilation rate per person shall be calculated:

where

qsp       total ventilation rate per person (L/(s person))

qs         design ventilation rate supplied by actual air distribution system, (L/s)

n          number of the persons in the room corresponding to typical occupancy [20] (-)

5.2.4 CO₂ concentration setpoint above the outdoor CO₂ concentration shall be calculated from metabolic CO₂ generation and CO₂ volume balance:

where

C          CO₂ concentration setpoint value above the outdoor CO₂ concentration (ppm)

qCO₂     CO₂ generation rate (L/(h person))

     3600 and 106 are unit conversions from hour to second and litre to ppm

5.2.5 As an alternative to 5.2.3 and 5.2.4, the following fixed CO₂ concentration setpoint values above the outdoor CO₂ concentration may be used:

·         500 ppm in rooms where floor area is >6 m² per person;

·         600 ppm in classrooms;

·         800 ppm in other rooms where floor area is <3 m² per person.

5.2.6 If ventilation is shut off for unoccupied periods, the system shall be switched on so that ventilation airflow volume corresponding to at least one volume of rooms will be delivered within 2 hours prior to occupation.

5.2.7 CO₂ setpoint values shall be used in the long term assessment of CO₂ concentration with IAQ simulations. Acceptable deviation from these values shall be no more than 5% during occupancy hours.

5.3 Operation for optimal indoor air quality in residential buildings

5.3.1 Ventilation system shall be operated at constant air volume or as demand controlled ventilation.

5.3.2 In the case of demand controlled operation, ventilation system shall maintain specified IAQ and humidity levels. Ventilation system may be operated in between design, as given in 4.3, and minimum ventilation rate so that CO₂ in living rooms and bedrooms, and relative humidity in wet rooms are maintained at specified levels. Acceptable deviations may be assessed as specified in 5.2.7.

5.3.3 Minimum ventilation rate [21] shall be at least 0.15 L/(s m²) of floor area.

5.3.4 Cooker hoods must be used in kitchens to remove cooking pollutants.

6. IAQ monitoring and regulation equipment [22] in non-residential buildings

6.1 New non-residential buildings shall be equipped with measuring and control devices as a part of a demand-controlled ventilation (DCV) system for the monitoring and regulation of IAQ.

6.2 New non-residential buildings shall be equipped with building automation and control systems [23] which provide monitoring of IAQ and temperature in continuously occupied spaces.

6.3 In major renovations 6.1 and 6.2 shall be followed as applicable.

6.4 IAQ regulation shall be applied at least in spaces that are intended for three or more persons.

6.5 IAQ regulation is not needed in spaces where ventilation requirements are determined predominately by extract air flow rates.

6.6 DCV systems should use sensors that can reliably measure parameters that are used for IAQ monitoring and regulation.

6.7 In DCV systems equipped with adequate outdoor air filters, CO₂ may be used as a parameter for IAQ monitoring and regulation. In zones where outdoor air intake without outdoor air filters is used, additionally the particulate matter PM2.5 shall be used for IAQ monitoring and regulation [24].

6.8 Monitored IAQ parameters shall be made visible in rooms for users, provided both by readings and traffic light colour type of indicators. They should also be available at least with hourly resolution for last 12 months in building automation and control systems for long term performance assessment and maintenance support purposes.

7. Noise from building service equipment

7.1 Building service equipment including ventilation, heating and cooling systems shall not cause disturbing noise. Indoor noise due to building service systems at design conditions shall not exceed the values specified in Table 4.

Table 4. A-weighted equivalent continuous sound pressure level, normalized with respect to reverberation time, LAeq,nT [dB(A)] [25] for continuous sources.

7.2 The values in Table 4 can be exceeded by maximum 5 dB (A) for a short-term period if the occupants can control the operation of the equipment.

8. Capacity to react to external signals and adapt energy use, generation or storage [26]

8.1 A capacity to react to external signals shall be implemented so that thermal comfort and IAQ are not compromised. Acceptable deviations may be assessed as specified in 3.6, 5.2.7 and 5.3.2.

Explanatory report for model IEQ regulation proposal

The model regulatory text proposal is accompanied with the explanatory report where the main choices made are explained and some alternative options are discussed. Explanatory report starts with explaining the most important IEQ parameters and how these can be controlled throughout the construction process, Table 5.

Table 5. An example of most important IEQ parameters. Minimum requirements specify design targets which compliance can be assessed with commissioning procedures. IEQ and energy performance can be assessed with continuous monitoring and inspection.

1) In addition to indoor values, monitoring of outdoor values for air temperature, humidity, CO₂ and PM2.5 is needed. The importance for IAQ is the difference of indoor-outdoor CO₂ and PM2.5.

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

3) PM2.5 continuous monitoring is not needed if particulate matter is controlled with filters in ventilation system, and there is no significant infiltration through building envelope.

IAQ monitoring and regulation equipment requirement in non-residential buildings is perhaps a most significant change in EPBD. It is explained how a demand-controlled ventilation systems (DCV) can be used and why simple time schedule and switching the system on/off is not enough to fulfil Article 13(5) requirements. Principal DCV control solutions classified as pressure-independent and pressure-dependent systems are discussed and some examples are provided. Figure 1 shows the most robust DCV implementation principle with on-off dampers. In this system all diffusers have constant airflow rates, and the control is less dedicated than in many other systems as based on switching on or off ductwork branches.

Figure 1. Pressure independent DCV system implemented with on-off dampers in larger rooms. Smaller rooms with one diffuser have constant airflow rates (CAV). Low-pressure design is recommended for main ducts that helps to keep a constant static pressure (AHU 1). The control itself is as robust as possible, room branch dampers are just opened or closed based on the local room sensors CO₂ and temperature readings. AHU2 (CAV) with time control but not DCV serves toilets and corridors.

Optimal IEQ and IAQ monitoring and regulation requirements in EPBD bring a need for long term evaluation of IEQ parameters. While national requirements will be specified, it is important that the parameters will stay within acceptable ranges. Explanatory report discusses this topic by taking an additional step of IEQ rating and labelling that is beyond EPBD requirements. The idea is, that it is possible to make IEQ visible using indicators and scales that are similar to energy performance certificate scale. Four categories, thermal, IAQ, light and acoustics, are needed to cover IEQ and these cannot be combined, because for instance, more light cannot compensate poor ventilation and vice versa. One possible IEQ rating and labelling scheme is TAIL [27] that was developed in EU ALDREN project. TAIL rating can be based either on measured or IEQ simulation [28] data, which IAQ ranges can be found from the explanatory report. TAIL rating scheme provides a label using traffic light colours for each IEQ category and the total IEQ rating that represents the lowest rating of any category, Figure 2. An ongoing EU Smart Living EPC project [29] has further developed the labelling scale to follow the same A-G categories as used in energy performance certificates, Figure 3.

Figure 2. An example of TAIL rating. In this case, thermal and light are in the highest category I, acoustics in the moderate II and IAQ in the lowest category IV. The building rating follows the lowest rating of a single category and is in this case IV.

Figure 3. IEQ rating using EPC scale of A-G developed in EU Smart Living EPC project.

References