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Application of ALDREN‑TAIL index for rating the indoor environmental quality of buildings undergoing deep energy renovation
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Wenjuan WieScientific and Technical
Centre for Building (CSTB), France | Corinne
MandinScientific and Technical
Centre for Building (CSTB), France | Pawel
WargockiInternational Centre for Indoor Environment and
Energy, |
Introduction
One of the
limitations for advancing indoor environmental quality (IEQ) in buildings is
the lack of a common metric or a set of agreed indicators for IEQ. Wei et al.
(2020) showed that nearly 100 different parameters are used to monitor and
express IEQ in different standards and certification schemes worldwide. Still,
no standard, uniform, and agreed metric have been developed so far. Deep energy
renovation (DER) of buildings intentionally or not intentionally affect IEQ.
DER, as a consequence, may have adverse effects resulting in discomfort,
increased risk for health, or reduced productivity, which needs to be detected
and immediately mitigated. But DER can also provide benefits of improved
comfort, health, and productivity that are not accounted for when the
cost-benefit analyses of building renovations are made. A fair conclusion will
be that IEQ is inadequately addressed during energy renovations because of the
lack of this standard metric.
ALDREN
project consequently developed an index that allows rating of IEQ in buildings
that are in operation and undergo DER as well as a method for predicting IEQ
during the design of DER (Wargocki et al., 2019a,
2019b, 2020). The former is called ALDREN-TAIL, in short TAIL, the latter is
called predicTAIL. In both cases, TAIL describes four
components of IEQ, i.e., thermal environment (T), acoustic environment (A),
indoor air quality (I), and luminous (visual) environment (L), as well as the
overall quality of the environment.
TAIL index
The TAIL
index consists of 12 parameters describing IEQ (Table 1).
The parameters are defined based on a review of the state-of-the-art of IEQ
indicators proposed by Green Building (GB) schemes, European standards,
research projects and scientific publications (Wei et al., 2020). They are also
aligned with the requirements of standards supporting the European Energy
Performance of Buildings Directive (EPBD). For each parameter, four ranges are
defined describing their four quality levels aligned with the quality levels
included in the standard EN16798-1. The four quality levels of the 12
parameters and the four IEQ components defining the ALDREN-TAIL index are
depicted with one of the four colors: green representing high-quality level,
yellow indicating medium quality level, orange showing moderate quality level,
and red representing low-quality level. The Roman numbers indicate the overall
IEQ level, i.e., I, II, III, and IV, corresponding respectively to green,
yellow, orange, and red quality levels (Figure 1). The
twelve parameters are determined before and after energy renovation using
measurements in buildings, observations (only visible mold), or simulations
(only daylight factor). The detailed protocol for measurements has been
developed. The quality level of each component of TAIL and the overall IEQ
level is determined by the lowest quality to create incentives for improvement
and not to compromise any of the major components of IEQ.
Table 1.
ALDREN-TAIL indicators.
T (thermal environment) | A (acoustic environment) | I (indoor air quality) | L (luminous environment) |
Air temperature | Sound pressure level | CO₂ | Daylight factor |
Ventilation rate | Illuminance | ||
Air relative humidity | |||
Visible mold | |||
Benzene | |||
Formaldehyde | |||
PM2.5 | |||
Radon |
Application of TAIL in
buildings before or after energy renovation
With the
ALDREN project, the TAIL has been applied in six buildings before or after
having been retrofitted to determine the quality of the indoor environment.
Below there is an example of measurements from one office building performed in
November 2019. According to the measuring protocol and given the size of the
building, eight representative rooms were selected for measurements. In each
room, the parameters defining TAIL (Table 1) were
determined; measurements were performed for one week using on-line
instrumentation and passive samplers. For temperature, the measurements were performed
over one month. The daylight factor was modeled. There were no visible signs of
mold.
The
measured values at each measuring point during working hours were compared with
their defined ranges (Wargocki et al., 2020), and
their quality levels were determined. The quality level of each parameter
defining TAIL was obtained by calculating the interim rating at each of the
eight measuring locations:
| (1) |
where R is the rank for the specific quality level k (R = 1
for green level, R = 2 for yellow
level, R = 3 for orange level and R = 4 for red level); O is the number of observed rooms for the specific
quality level k; k
is the number of quality levels (k ≤ 4);
n is the total number of the rooms where
measurements are performed.
The final
quality level of each of the four TAIL components at the building level was
determined by the worst interim rating for the thermal environment (T),
acoustic environment (A), indoor air quality (I), and the luminous environment
(L). The overall rating of IEQ was determined by the worst level of the four
TAIL components.
Figure 1 shows the TAIL level of the
building. The thermal environment in the building (T) was qualified at the yellow
level because the indoor air temperature varied between 20 and 24°C during more
than 94% of the working hours in 5 rooms. The thermal environmental quality
could be improved to the green level if the indoor temperature had been reduced
to 23°C during midday. The acoustic environment in the building (A) was
qualified at the green level because the sound pressure was lower than
35 dB(A). The indoor air quality in the building (I) was qualified at the
orange level mainly because CO₂ concentrations in the measured rooms
often exceeded 1200 ppm, and there were high concentrations of formaldehyde.
The indoor air quality could be improved by increasing the air change rate in
highly occupied spaces. The luminous environment in the building (L) was
qualified at the orange level because the median daylight factors in the
selected rooms were between 1.7% and 3%, and the illuminance levels in the
measured rooms were often higher than 500 lux at the desk height. The
visual environment could be improved by renovating sun protection systems and
reducing artificial lighting.
Since the
lowest quality level among TAIL components was orange, the overall quality
level of IEQ and the overall rated TAIL level was also orange, which is
represented by the Roman III in the middle of the TAIL indicator for this
building (Figure 1).
Figure 1.
TAIL level of an office building.
Predicting TAIL index: PredicTAIL
Because the
TAIL index should guarantee a good IEQ after the energy renovation, it must
also be possible for the building owners or investors to assess what could be
the influence of the different renovation actions on IEQ. For this purpose, the
predicTAIL index was created. PredicTAIL
includes the same IEQ parameters, the same quality levels and the same
calculation method as TAIL, but is purely based on modeling. PredicTAIL is modeled before renovation to serve as the
baseline, and then it is modeled for different renovation strategies. By
comparing PredicTAIL after with PredicTAIL
before energy renovation, the best renovation strategy can be chosen. PredicTAIL is an additional tool for decision making and is
not a verification tool for TAIL. Both should be used independently.
Conclusions
TAIL
creates an incentive to improve IEQ as well as the framework that allows
qualitative and quantitative assessment of non-energy benefits resulting during
the process of a deep energy retrofit. The TAIL index focuses on office and
hotel buildings to be aligned with the ALDREN procedure, but the intention is
to use it in any type of building.
Being
measured before the renovation, the TAIL index helps to identify the possible
components to be improved on the occasion of the energy renovation, making the
latter even more beneficial for the building and its occupants. In case of
measurements done after the energy renovation, the TAIL index ‘after’ compared
to the TAIL index ‘before’ helps in showing that the renovation has not
degraded the IEQ in the building or whether the IEQ improved.
Interview with |
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1. Is there a need for an IEQ indicator, and
why?The ALDREN initiative is certainly very promising. To have a
comprehensive indicator of indoor environment quality corresponds to a real
preoccupation of all professionals in the search of complete evaluation of a
building quality. The complete evaluation of health and overall comfort
conditions indoors is necessary to assess the quality of use of a building,
the definition of a first aggregate indicator even if it is not integrating
every single aspect of IEQ is a real progress in this way. 2. Does TAIL fulfil this need, and why
(benefits of TAIL)?In my opinion TAIL answers this need. In order to be efficient and used
by professionals, the IEQ indicators need to be as complete as possible,
built on solid scientific basis and easy to understand. We already have many
environmental quality indicators used by environmental quality assessment
methods everywhere in the world but all of them are based on a long list of
individual indicators which makes difficult to have a clear vision of the
overall quality. For me, the TAIL method fulfills this need. 3. Do you think TAIL would be accepted by
building professionals?It is always very difficult to predict the acceptability of a method or a
concept. However, TAIL is quite attractive by its apparent simplicity. It is
complete, easy to understand, and efficient in the overall approach to the
assessment of indoor environment quality. I really think it will be accepted
easily by our professionals. 4. What should be next step in developing
TAIL?TAIL needs to be tested in different types of building types (offices,
residential, schools, etc.) in a wide range of climates. The testing
protocols have to be evaluated carefully to strengthen the method and the
limits of such a complete IEQ indicator have to be clearly stated. Then, this
indicator could be used easily in the evaluation of rehabilitation projects.
Most of the projects are focusing mainly on the energy performance and it
will be a real benefit to add this IEQ indicator. | |
Interview with |
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1. Is there a need for an IEQ indicator, and
why?IEQ indicators and other health-based criteria and requirements are given
emphasis in a number of building related policy and legislative instruments
(e.g. amended EPBD, Construction Products Regulation, European standards and
national regulations, etc.). However, a major obstacle for integrating energy
and IEQ strategies in the design and optimisation
of buildings is the lack of a common, quantitative metrics for IEQ although
the worldwide definitions of IEQ generally agree about the main components
contributing to the IEQ of buildings and IEQ is considered in existing GBC
schemes. Therefore, there is need for a commonly defined and accepted IEQ
indicator in EU and worldwide. 2. Does TAIL fulfil this need, and why
(benefits of TAIL)?TAIL is among the IEQ indicators, indices and tools, which were recently
reviewed by EC Services (DG ENER & DG JRC) regarding their potential to
be used in the process of IEQ data integration into the EU Building Stock
Observatory. TAIL was developed as result of an extensive review process,
which can be regarded as a reference for selecting parameters and for
development of IEQ indicators that are commonly used in energy performing
buildings. Moreover, it is compliant with major certification schemes,
EN16798-1 and Level(s). Therefore, the TAIL method can be directly used in
the process of defining and applying a common IEQ metric addressing the EU
building stock. 3. Do you think TAIL would be accepted by
building professionals?TAIL has the potential to attract the interest of investors in IEQ and of
building professionals, as it can be determined with small extensions to the
measuring protocol when performing building certification using major Green
Building and Sustainability Certification Schemes. TAIL ranks among the top
IEQ concepts and methodologies which were reviewed by EC which present high
degree of comprehensive use and affordability to end users, however, needs to
undergone validation before it can be effectively applied beyond the purpose
for which was developed and after having assessed the feasibility and
flexibility of its application at various scales (local, national, EU),
buildings’ typologies and assessment objectives. 4. What should be next step in developing
TAIL?Further development of TAIL should be driven by the need of defining and
applying a harmonised IEQ indicator at EU level at
affordable cost, to assess IEQ in energy performing buildings via a
well-balanced and complementary approach of objective (i.e. via measurements)
and subjective (i.e. perceived IEQ) assessment which considers the following
aspects: variation of IEQ parameters over time (e.g. variation of a calendar
year, or different seasons); flexibility for application across different
typologies of buildings and different objectives of assessment; need for
adjusting IEQ parameters and their weighting according to different national
contexts and specificities in EU MS. | |
Acknowledgement | |
This project has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement 754159. The sole
responsibility for the content of this paper lies with the authors. It does
not necessarily reflect the opinion of the European Commission (EC). The EC
is not responsible for any use that may be made of the information it
contains. |
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References
Wargocki,
P.; Mandin, C.; Wei, W.; Espigares,
C.; Bendzalova, J.; Greslou,
O.; Rivallain, M.; Zirngibl,
J.; Assessment of indoor environmental quality (IEQ) in offices and hotels
undergoing deep energy renovation – the ALDREN method. REHVA Journal, 2019a,
51-53.
Wargocki, P.; Mandin, C.;
Wei, W.; ALDREN-TAIL index for rating IEQ. ASHRAE Journal, 2019b, 66-68.
Wargocki, P.; Wei, W.; Anton, R.; Bendžalová,
J.; Espigares-Correa, C.; Gerard, C.; Greslou, O.; Rivallain, M.; Sesana, M.; Zirngibl, J.; Mandin, C.; ALDREN-TAIL: a new index for assessing indoor
environmental quality in offices and hotels undergoing deep energy renovation.
To be submitted.
Wei,
W.; Wargocki, P.; Zirngibl,
J.; Bendzalova, J.; Mandin,
C.; Review of parameters used to assess the quality of the indoor environment
in Green Building certification schemes for offices and hotels. Energy &
Buildings, 2020, 209, 109683.