Authors: Pawel WARGOCKI (DTU), Corinne MANDIN (CSTB), Wenjuan WEI (CSTB)

May 2019, Full article: click here

One of the main thrusts of ALDREN is benchmarking the quality of the indoor environment (IEQ) in buildings that have undergone DER. The reason for this is threefold: 1) to guarantee that IEQ is not degraded during renovation to satisfy the EPBD mandate; 2) to document any improvements in IEQ after renovation; and 3) to estimate potential additional benefits from renovation including benefits for health and well-being, as well as the financial benefits from improved productivity and increased value of a building on a market.

To address the need for benchmarking IEQ in a building undergoing DER, a new index was proposed within the framework of ALDREN. The index is used to document IEQ in a building before and after renovation. The index is called ALDREN-TAIL, in short TAIL. It embraces four major components of IEQ, namely:
• thermal environment (T),
• acoustic environment (A),
• indoor air quality (I),
• luminous (visual) environment (L).

The TAIL index provides information on the quality of each of these four components. The quality level is described by four colors:
• GREEN standing for high quality,
• YELLOW for medium quality,
• ORANGE for moderate quality
• RED representing low quality.
These four colors are used because of their familiarity to building stakeholders and to enable simple communication.

The overall quality of the indoor environment is derived using the quality levels of each of the four components of the TAIL. The overall level of IEQ is the lowest quality level among the four components to create an incentive to improve IEQ. The overall quality level is indicated in the middle of the TAIL index by a Roman number, where:
• I stands for high quality,
• II for medium quality,
• III for moderate quality,
• IV for low quality.
The Roman numbers are used to match the quality levels with the categories of the indoor environment defined by the EN standard 16798-1 (2019), one of the many standards supporting the implementation of EPBD.

Twelve parameters were chosen to describe the level of IEQ using the TAIL index:
• the temperature in different seasons is used to describe the thermal environment (T),
• noise level is used to characterize the acoustic environment (A),
• ventilation rate, concentrations of carbon dioxide, formaldehyde, benzene, PM2.5 and radon, relative humidity and visible mold are used to describe indoor air quality (I),
• illuminance and daylight factor are used to characterize the luminous environment (L).

Except for a few parameters characterizing indoor air quality, the parameters describing IEQ in TAIL refer to conditions required for comfort. The parameters documenting IAQ conditions that reduce health risk comply with the WHO air quality guidelines.

The twelve parameters were selected by summarizing the parameters used to characterize IEQ in building certification schemes, EN standard 16798-1 (2019) and Level(s) (2019) – an EU’s voluntary reporting framework to improve the sustainability of buildings. This was done so that parameters that form TAIL are widely accepted as markers of IEQ and they are frequently used by different certification schemes and standards. From the beginning, the premise was that TAIL, which is supporting DER performed following the framework provided by EPBD, should by compliant with documents that are prepared by the European Commission and standards supporting EPBD, as well as that it should be possible to determine TAIL when performing building certification using major building certification schemes. This was done to ensure adoption and market uptake. To this end, TAIL is compliant with Level(s), Well, HQE, DGNB, LEED, and other certification schemes.

The levels and ranges of the twelve parameters defining different quality levels were determined also using the summary of certification schemes. It was decided that the quality levels of parameters underlying TAIL are not determined by the arbitrary credits assigned to different parameters but by the actual levels determined by measurements (and observations in case of mold and simulations in case of daylight factor).

Objective measurements using calibrated instruments have been chosen as the main method for the assessment of IEQ. Visible mold shall be assessed by observations as no other evaluations can be made, while daylight factor can only be modelled. In case the measurements are not possible, modelling is allowed, but it is not considered as the primary method for evaluating of IEQ due to too many assumptions that should be made regarding the existing building undergoing DER. Subjective measurements were not included as the rating method because no standard validated methods exist allowing credible assessments using responses of building occupants and particularly comparisons of ratings across different buildings.

The detailed protocol for determining TAIL was developed. It includes the temporal and spatial sampling strategy, definition of the minimum number of locations (rooms) per building that shall be instrumented during measuring campaign, details on instruments that shall be used for performing measurements and their minimum precision, and description on how the results of measurements shall be analyzed. It also describes when the measurements can or shall be supplemented or replaced by modelling or observations. This protocol is now being examined within the scope of ALDREN project.

In summary, the proposed ALDREN-TAIL index creates the framework for a rating of IEQ and its components. TAIL is an integrated index, an indicator of IEQ in buildings that undergo DER. TAIL complements the existing approaches for assessing IEQ and is compliant with the major certification
schemes. All components of the TAIL are treated equally: To achieve the high quality level, all components of the TAIL must be at the high level, and no compromises are accepted. The use of TAIL must be validated and the necessary revisions and supplements to the protocol used for deriving TAIL should be made. Although TAIL has been developed to document IEQ in offices and hotels, it is expected that TAIL can be extrapolated to residential buildings and most likely schools as well. This would, however, require additional validation.

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