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Environmental Engineering and Management Journal November 2013, Vol.12, No. S11, Supplement, 229-232http://omicron.ch.tuiasi.ro/EEMJ/

Gheorghe Asachi Technical University of Iasi, Romania

ADVANCED TOOLS FOR THE MONITORING AND CONTROL

OF INDOOR AIR QUALITY AND COMFORT

Extended abstract

Gian Marco Revel1

, Marco Arnesano1, Filippo Pietroni

1, Jrgen Frick

2, Manuela

Reichert2, Markus Krger

3, Katrin Schmitt

4, Jochen Huber

4, Martin Ebermann

5, Luc

Pockel6, Ariane Khanlou7, Antonia Ekonomakou7, Johann Balau8, Carmine Pascale9,Francesco De Falco

9, Roberto Land

10, Umberto Battista

10, Jay Stuart

11

1Universit Politecnica delle Marche , Department of Industrial Engineering and Mathematical Science, Ancona, Italy2University of Stuttgart, Materials Testing Institute Stuttgart, Germany, 3TTI GmbH TGU Smartmote, Stuttgart, Germany,

4Fraunhofer Institute for Physical Measurement Techniques, Freiburg, Germany, 5InfraTec GmbH, Germany, 6R.E.D. srl, Italy7S&B Industrial Minerals S.A., Greece, 8SCHWENK Putztechnik GmbH & Co. KG, Hindenburgring, Germany, 9Consorzio TRE,

Italy, 10STAM Srl, Genova, Italy, 11DELAP & WALLER ECOCO LIMITED, Dublin, Irelanda

Background

New and refurbished buildings in Europe have to meet requirements concerning thermal insulation and air

tightness, as well as primary energy demand for heating, illumination, ventilation and air conditioning. In future netzero energy buildings will be the state of the art. The refurbishing to an energy efficient standard leads to tightbuildings (whole envelope: windows, walls etc.) and affects the indoor climate. In case of refurbishing the

inhabitants or users are not adapted to this new situation. Therefore the air exchange rates could be lower thanrequired if no mechanical ventilation is installed or the system performance is not optimized. Then, in trying toincrease the energy performance of buildings, the indoor environment quality is often degraded due to the lack ofexchange with the outdoor environment.

People in Europe spend more than 90% of their time indoors (living, working and transportation). In morethan 40 % of the enclosed spaces, people suffer from health- and comfortable related complains and illness. Alreadyin 1984 the WHO reported an increased frequency in buildings with indoor climate problems. The complexity of

the problem and the fact of building related symptom clusters were later described as Sick Building Syndrome(EPA, 2009). Major symptoms of Sick Building Syndrome observed are allergy, lethargy, headaches, dry eyes, throatand skin. Office indoor air may also be associated with productivity and sick leave of the office occupants (Mendell,

2007). Improving the health and comfort of the European population in those spaces consequently create a hugepotential of economic and societal benefits, manifested in increased productivity, reduced sick leave and medicalcosts, but also by the prevention of potential liabilities. The FP7 European project called Cetieb (Cost-EffectiveTools for Better Indoor Environment in Retrofitted Energy Efficient Buildings www.cetieb.eu) is moving towardsthis objective. The modular system for the monitoring has been developed in order to measure several parameters

such as VOC (Volatile Organic Compound), RGB (Red, Green and Blue) luminance and CO 2. In addition, thesystem includes the measurement of environmental variables as the thermo-hygrometric comfort using an innovativesensor for retrieving the PMV index (Predicted Mean Vote). The control of the air quality relies on active systems foractuating the mechanical ventilation, with or without bio-filters, starting from monitored variables. Moreover, thedevelopment of passive technologies for the control of indoor environments completes the tools set with the use ofphoto-catalytic plasters for the air cleaning or light materials with low thermal conductivity. The aim of the paper isto present the main research lines of the CETIEB (begin October 2011 - end September 2014) project in this contextwith a focus on the innovative aspects of the expected results.

Author to whom all correspondence should be addressed: e-mail: [email protected]


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Objectives

The main objective of the project is to develop and integrate innovative solutions for better monitoring theindoor environment quality and to investigate active and passive systems for improving it. The focus lies on cost-effective solutions to ensure a wide application of the developed systems:

Development of monitoring systems (wireless and/or partly wired) to detect indoor environmental comfort andhealth parameters. A modular version will be developed to allow end users a quick check of the indoor air quality.

Development of control systems to optimize the indoor environment quality and energy efficiency. Measures areinnovative passive plaster materials using photo catalytic and phase change materials, plant based bio-filters, andactive air flow controlling components. Provision of alarm values for action, if automatic control is not sufficient.

Modeling of indoor environments for the assessment and validation of monitored data to optimize the controlparameters and systems.

Monitoring and measurement tools

The CETIEB project is aimed to deliver a cost efficient wireless or partly wired system especially designedfor monitoring indoor environment parameters. The monitoring and measurement technologies developed within the

project will be a step forward in terms of: (i) provision of cost-effective and simple to use monitoring systems thatallow for monitoring of a large variety of indoor environmental factors; (ii) provision of advanced sensortechnologies to better measure and assess indoor environment factors with respect to human health and well-being;(iii) Provision of data collection and analysis software that could be used to better monitor, assess, evaluate and

control the indoor environment.Short and long-term monitoring systems require the application of specific sensors. Although a lot of

commercial sensors for determining air quality and comfort are available, there is a demand to develop sufficientsensors that are optimised for the monitoring task. This could be with respect to cost-effectiveness or higher

accuracy, precision or reliability. Such sensor technologies could be either integrated into the portable wirelessmonitoring system or could be integrated into active control systems for permanently improving the indoor

environment. Several types of sensors are being developed within the project, e.g. VOC (with medium and highsensitivity), CO2, thermal image sensors (infrared sensors for multi-point temperature analysis), and indoor lightspectrum.

1. Detection of VOC

One key challenge within the project is the detection and monitoring of Volatile Organic Compounds(VOC) for the assessment of health related parameters. Actually, there is an increasing demand to obtain more

spectral information in many gas sensing applications, particularly with regard to the analysis of multi-componentmixtures, reducing cross-sensitivities between adjacent and overlapping absorption bands and to lower detectionlimits. Infrared absorption spectroscopy as a broadband and selective measuring principle potentially fills this gap.Based on substance-specific absorption spectra the discrimination between the components of a mixture and aquantitative measurement of their concentrations is possible. In particular the wavelength ranges of 3 5 m and 8 12 m (mid and long wave infrared) are of interest. The hybrid integration of a bulk micro machined high finesse

Fabry-Perot Filter and a pyroelectric detector results in a very compact spectrometer module. Existing instrumentdesigns can be easily adapted to such a tuneable detector. InfraTec has developed such devices for the spectral range

of 3 5 m and 8 11 m (Ebermann at al., 2010).As a VOC representative acetaldehyde (CH3CHO, peak absorption at 3.65 m) was measured in nitrogen in

the concentration range from 0 to 25 ppm (Fig. 1). The achieved resolution is better than 5 ppm. From literature themaximum values of single VOCs like acetic acid (CH3COOH) could be up to 2.3 ppm (5698 g/m

3) in newshowcases or up to 1.9 ppm in storage cabinets (average 4.7 mg/m3). Therefore the real-time detection of singleVOCs is visible if the detection range could be further improved.

2. IlluminationThe region of light the eye can see (visible region) consists of light with a wavelength between

approximately 380 nm to 780 nm. The obvious way to measure this would be with a spectrophotometer, whichmeasures the light intensity in function of the wavelength at intervals of e.g. 5 nm.

An alternative way is the use of a so called RGB sensor. These sensors are silicon based photo-sensorsmeasuring radiation from 300 nm to 1100 nm overlapping the photonic response of the human eye. The unwanted

radiation (IR and UV) needs to be filtered. In addition, Red, Green and Blue filters based on the colour matchingfunctions defined by the CIE are reproducing the RGB values as if they were observed by the human eye. Now,instead of hundreds of values coming from the measurement of the spectrum by a spectrophotometer, only fourvalues are given by the sensor: clear (only filtered for IR and UV), Red, Green and Blue. These values can betransformed into XYZ values in the CIE colour space. Obviously, the filters of the sensors do not match completelythe colour matching functions of the CIE and need to be calibrated. Within the CETIEB project such a low-cost

sensor solution for light intensity and light spectra was realized. The sensor has been developed to determine theColour or Correlated Colour Temperature of white light with the objective to simulate the natural colour

temperature of daylight in function of the time of the day and the latitude of the location. It can be integrated in the


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Advanced tools for the monitoring and control of indoor air quality and comfort

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monitoring system described above, in turn driving the illumination system. This low cost RGB based colour sensor

consists of a packaged optical sensor (TAOS TCS3414CS), diffuser, IR filter and housing. The sensor has beentested providing RGB and total light values when requested to the monitoring software on the PC. These are thenecessary values to determine the total illumination level (lux) and the colour temperature of the light.

3. Comfort measurementAnother innovation of the CETIEB project is the development of a low-cost infrared system for real-time

measurement of human thermal comfort performed by Universit Politecnica delle Marche. The monitoring device,including a set of sensors in a bulk unit, can be installed on the ceiling of the occupied room. The system measureson indoor surfaces and environment to derive comfort parameters (as Predicted Mean Vote PMV) for severalpositions in the space. Since the measurement is not a single-point one and is not only based on temperature, theHVAC control strategy can be improved which offers potentials of energy savings. PMV is the average comfort vote,using a seven-point thermal sensation scale, predicted by a theoretical index for a large group of subjects whenexposed to particular environmental conditions. As indicated in Eq. 1 the PMV is affected both by environmental

parameters (air temperature ta, relative humidity RH, mean radiant temperature tr, air velocity va) and subjectiveparameters such as the metabolic rateMand the clothing insulationIcl.

PMV = f(ta, RH, tr, va, M, Icl) (1)

Mean Radiant Temperature (MRT, tr) appears to be one of the most influential parameters in order toprovide a good estimation of PMV (metabolic rate and insulation can be set constant). Therefore a measurement

system for a good estimation of this parameter is needed. The system is adopted to provide real-time measurement ofthermal images of the indoor environment and derive comfort parameters. Basics of the system are shown in (Revelet al., 2012). Advanced signal processing algorithms allow the calculation of thermal comfort parameters by takinginto account all sources and thermal loads in the room (Fig. 2).

Fig. 1. Sensor developed (left) and measurement of acetaldehyde in N2from 0 to 25 ppm in 5 ppm steps (right)Fig. 2. Principle sketch of thermalcomfort measurement system scenario

The thermal image sensors find several fields of applications, from industrial to sanitary, public andresidential, where providing an adequate comfort condition to occupants is essential. The system could be of specialinterest also for museums and cultural heritage buildings with respect to energy savings and protection purposes.

Active and passive methods for indoor environment improvement

1.VentilationVentilation has important energy consequences. In case heating or cooling is required, the energy penalty is

the most important reason to minimise the amount of ventilation. In most climates, the supply of outdoor air has aninfluence on the energy use for heating, cooling, humidification and dehumidification. In case of additional energyuse from fans or HVAC (Heating, Ventilation, and Air Conditioning), this will result in additional outdoor pollution.However, ventilation can also reduce the energy need, e.g. in case of an efficient strategy of night-timeventilation/cooling. In a study (JRC, 2003) on ventilation and its effects on energy and indoor air quality (IAQ), theJoint Research Centre estimated that ventilation can constitute up to 50% of energy use in buildings. Considering

energy-efficiency isolated, natural ventilation is often a preferred strategy compared to mechanical or fan-forcedventilation (JRC, 2007). According to Seppnen (1998), the developing technologies of natural ventilation and free

cooling can improve energy efficiency for a given IAQ up to 60%. The main innovation of the active system will beto enable controlled natural ventilation and thus the conditions for drastically improved IAQ and optimal air flowcontrol in buildings. Combined, the two benefits of improved energy efficiency and controlled natural ventilationwill effectively decouple the negative correlation between thermal properties and IAQ. In addition, the HVACcontrol system under development includes a control loop which takes in account not only the merely air temperatureas comfort parameter, but the PMV, which, as explained above, is an index obtained from six different variables ofthe environment and of the occupant.

2. Thermal insulation

Another goal of the project is the development of mineral-based thermal insulating lightweight mortars by theuse of phase change materials (PCM) in combination with expanded perlite. With the addition of PCM, the heatcapacity of mortars will be increased and walls will adsorb or release energy (heat) from the indoor environment


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