ScienceDirect Publication: Building and Environment

April 2013
Publication year: 2013
Source:Building and Environment, Volume 62

A framework was developed for integrating indoor environmental quality (IEQ) into life cycle assessment (LCA). The framework includes three main impact types: 1) chemical-specific impacts directly comparable to conventional life cycle impact assessment (LCIA) human health categories, 2) non-chemical health impacts, and 3) productivity/performance impacts. The first part of the framework related to contaminant specific impacts was explored using a green university building as a case study, while the remaining categories will be the subject of future work. Results showed that including IEQ aspects in whole-building LCA revealed LCIA internal impacts in some categories comparable to external impacts. For human health respiratory effects, building-specific indoor impacts from the case study were 12% of global external impacts in conventional LCA. Building-specific indoor cancer toxicity impacts were greater than external impacts by an order of magnitude, and building-specific indoor noncancer toxicity impacts were lower than external impacts by an order of magnitude. Although internal impacts were greater than external impacts in one category – cancer toxicity, the source of the contamination in the other two categories – respiratory effects and noncancer toxicity – was related to intake of outdoor air. The findings of this study underscore the importance of filtration or other treatment of mechanically supplied outdoor or recirculated indoor air, as well as control of pollution from indoor sources such as building materials or cleaning products. These findings may support the use of green building rating systems which include acknowledgment of the aforementioned IEQ-related features.

Highlights

► We outline a framework for including whole-building IEQ effects in LCA. ► We explore the portion of the framework pertaining to internal chemical impacts. ► We use a case study of an LEED Gold academic building to illustrate application. ► Internal impacts were comparable to or greater than external impacts. ► Internal human health impacts should be included in whole-building LCA.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

Wind-induced natural ventilation is beneficial to assure thermal comfort and to reduce cooling load in the hot and humid summertime. In the urban environment, where buildings are grouped closely, it is often difficult to obtain a large enough wind pressure difference to drive the natural ventilation. As architectural feature, this work focuses on “monitor roof” which has the potential to promote wind-induced natural ventilation, and aims to evaluate its ventilation performance. This paper analyses a two-story residential building model equipped with a monitor roof which is built in a long building row, assuming a densely populated residential area. Since the monitor roof shows complicated flow resistance, the conventional method to predict flow rate cannot be easily applied. Based on the correlation between internal pressure and flow rate, and wind pressure coefficients obtained from previous work, a simplified estimation method of flow rate is first applied in this paper. In addition, more detailed flow characteristics inside the room are analysed by Computational Fluid Dynamics using a Reynolds-Averaged Navier–Stokes model, and a certain level of accuracy is verified by comparison with wind tunnel measurement. By comparing flow rate between numerical simulation and measurement, the validity of the simplified estimation method is also verified. To analyse substantial ventilation performance including the effect of turbulence, numerical simulation using Large Eddy Simulation is also performed and particle tracking technique is applied. Based on those results, Purging Flow Rate is evaluated, and it is finally shown that the monitor roof can work well to promote natural ventilation.

Highlights

► Natural ventilation performance of the monitor roof is studied in this paper. ► The flow rate based on mean velocity is first evaluated by using p–Q correlation. ► More detailed airflow field is investigated by CFD where RANS and LES are applied. ► Actual ventilation performance is finally evaluated based on Purging Flow Rate.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

The pandemic H1N1 2009 (p-H1N1) spreading worldwide has led to severe morbidity and mortality. This study aimed to quantify the impacts on disease control by applying various control strategies for p-H1N1 in an elementary school indoor setting. Indoor disease transmissibility was explored by a general Wells-Riley equation. To better contain influenza outbreak, a multi-control measure model was developed. A non-extinction branching process was presented to quantify the indoor epidemic probability for seasonal influenza and p-H1N1. The infection risk, quantum generation rate (quanta d⁻¹), basic reproduction number (R 0), generation time (d), and asymptomatic infectious proportion (%) were, respectively, estimated to be 0.020 (95% CI: 0.010–0.043), 494 (140–1292), 3.30 (0.75–11.47), 3.54 (3.15–3.99), and 15 (8–59) for p-H1N1. By implementing all non-engineering interventions, seasonal influenza could be well controlled, whereas for p-H1N1, engineering and non-engineering control measure combinations were effective for complete outbreak containment. Indoor epidemic probability of p-H1N1 increases with increments in R 0 and introductions of infected individual. The proposed control strategies combined with non-engineering and engineering interventions could effectively control p-H1N1 outbreak. A multi-control measure model developed here could be implemented in more complex infectious circumstances. Our study can be incorporated into the relationship among influenza virus, host, and indoor environment for better understanding the complex dynamics of environmental processes and to achieve optimal indoor control measures.

Highlights

► Optimal control measures can be achieved in an elementary school. ► General multi-control measure model can be used in complex infectious conditions. ► Epidemic probability model captures the idea of alterations in indoor epidemic. ► Complex interactions among virus, host, and indoor environment can further be studied.

Available online 1 March 2013
Publication year: 2013
Source:Building and Environment

In Europe, high energy consumption in built environments has raised the need for developing low energy heating systems both in new building and in retrofitting of existing buildings. This paper aims to contribute by presenting annual results of calculated and measured energy consumption in five new-built semi-detached dwellings in Stockholm, Sweden. All buildings were equipped with similar low-temperature heating systems combining under-floor heating and ventilation radiators. Exhaust ventilation heat pumps supported the low-temperature heating system. Buildings were modeled using the energy simulation tool IDA Indoor Climate and Energy (ICE) 4, and energy consumption of the heat pumps was measured. Results showed that calculated and measured results were generally in agreement for all five dwellings, and that the buildings not only met energy requirements of the Swedish building regulations but also provided good thermal comfort.

Highlights

► A ventilation radiator is one type of low temperature heating systems. ► Energy performance in buildings with ventilation radiators was investigated. ► Dwellings with ventilation radiator met Swedish energy requirements for buildings. ► Ventilation radiators provided a good level of thermal comfort

Available online 1 March 2013
Publication year: 2013
Source:Building and Environment

Children are relatively sensitive to health pollutants, including those in indoor environments. This study was conducted to explore the impact of a water-damaged indoor environment on children’s weekly absences resulting from upper respiratory infection in a kindergarten. Twenty-six and 27 children were recruited from water-damaged and non-water-damaged classrooms in the same building, and 936 and 1,017 person-weeks were followed up during the study period of 42 weeks.

Weekly absence rates were computed from daily absence records. The weekly absence rate was significantly higher for children in the water-damaged classroom (2.99%) than for those in the non-water-damaged classroom (1.28%). After adjusting for gender and grade, the odds ratio for absence was 2.45 (95% CI: 1.15－5.24) for the children in the water-damaged classroom. Additionally, fungal concentration was significantly higher in the water-damaged classroom (993 CFU/m³) than in the non-water damaged classroom (404 CFU/m³). It is tentatively concluded that, in the subtropics, fungal concentration is a better indicator than humidity for early-stage water damage. Periodic fungal measurement is recommended to alter the water-damaged effect.

Highlights

►The absence rate comparison between water-damaged and non-water-damaged classroom is presented. ► An odds ratio 2.45 indicated more absences occurred in the water-damaged class. ► Higher fungal concentration was detected in the water-damaged classroom.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

We look critically at the principal graphs relating thermal comfort indoors to the climate, and compare the metrics used for the climate; an exponential running mean of the mean outdoor temperature proves better than either the historic monthly mean or the current outdoor temperature. Using the SCATs and the ASHRAE RP-884 databases of field-studies we develop a method to derive a standard sensitivity to indoor temperatures change. People are more sensitive to temperature change within a single working day than previously thought. This sensitivity is used to estimate the comfort temperatures and to establish a curve relating the probability of discomfort to the temperature-difference from the current optimum. Using the standard sensitivity, a reliable estimate of comfort temperature can be made from a small batch of data, and from batches whose summary statistics alone are known. This extends the quantity of available data from which to form the relation between indoor comfort and the climate. We draw on an extensive database of such summary statistics. Using this information the graphs relating the temperature for comfort indoors and the climate are updated. Bands are given within which the comfort temperatures are likely to lie, both for the free-running mode of operation and for the heated-or-cooled mode. The underlying mechanism of the relation between climate and indoor comfort is discussed. The data show that it is possible to design buildings to operate in the free-running mode so as to be comfortable when the prevailing mean outdoor temperature lies within the range 10–30 °C.

Highlights

► An extensive database of summary statistics confirms general pattern of relation. ► Best metric for outdoor temperature an exponential running mean with alpha 0.8/day. ► People more sensitive to within-day temperature changes than thought (0.5votes/K). ► Graph of comfort temperature versus outdoor temperature is steeper (0.53/K). ► Free-running mode possible if mean outdoor temperature between 10 and 30 °C.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

External Thermal Insulation Composite Systems – ETICS are, now-a-days, quite common in European buildings, used both in new constructions and refurbishment. Unfortunately, ETICS can have serious problems of biological growth causing the cladding defacement. It is known that biological growth is due to high values of surface moisture content, which results mostly from surface condensation and wind-driven rain. If the drying process is not sufficiently fast, the surface moisture content remains high for longer periods and consequently increases the risk of biological growth.

This paper presents the results of a detailed experimental study that was carried out by the Building Physics Laboratory of Porto University (UP), in order to assess the hygrothermal behaviour of façades covered with ETICS, namely to evaluate the influence of orientation on surface humidification, by external condensation and by wind-driven rain. A building located in UP campus, with its four façades facing the cardinal directions, was monitored during one year. The exterior surface parameters under study were temperature, long wave radiation, wind-driven rain and relative humidity. The exterior climate was also measured to evaluate surface condensation.

Highlights

► A test campaign was carried out to assess the hygrothermal behaviour of ETICS. ► The influence of orientation on surface water content was evaluated. ► The parameters assessed were temperature, long wave radiation, WDR and relative humidity. ► Orientation has major influence on surface condensation and WDR. ► The drying process has a key role of in the surface water content.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

The performance of ceiling-mounted personalized ventilators (PV) in reducing particle migration between office stations was assessed. The PV nozzles were integrated with peripheral diffusers that were able to form a canopy of conditioned air around the occupant. A numerical CFD model was developed to simulate the flow, temperature and particle concentration fields. Validation against experimental measurements and published experimental data was performed. The canopy was effective in reducing the migration of particles from the macroclimate to the microclimate region and low intake fractions of 1.90 × 10⁻⁴ and 5.9 × 10⁻⁴ were achieved for particle sizes of 1 μm and 0.01 μm, respectively. The PV jet was capable of maintaining an intake fraction of 3.6 × 10⁻⁴ for fine particle sizes (1 μm) and 2.95 × 10⁻⁴ for ultrafine particles (0.01 μm) when the particle-emitting source is in the proximity of the occupant. However, in spite of the good inhaled air quality achieved by the PV nozzle, the particle deposition rate on solid surfaces that are easily reached by the occupant is high when the source is placed in the microclimate.

Highlights

► A ceiling-mounted coaxial PV nozzle was modeled. ► Particle transport and distribution was investigated using two sources locations. ► The predicted flow characteristics were validated experimentally. ► The nozzle was able to deliver improved air quality to the occupants breathing zone. ► The canopy provided a protective zone by reducing particles migration.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

Building energy simulations are mostly implemented using network or multi-zone models that do not consider indoor air temperature and velocity distribution. However, the recent introduction of personal ventilation, floor-heating systems, and displacement ventilation positively utilizes a nonuniform indoor environment to meet the demand for both energy efficiency and thermal comfort. Therefore, it is expected that building energy simulation results will be significantly impacted by the choice of an appropriate reference air temperature for the calculation of heat transfer through constructed materials. This means that the air temperature distribution needs to be taken into account for nonuniform environments when carrying out energy simulations. An alternative approach to this problem is to combine a computational fluid dynamics (CFD) simulation directly with a network model; however, this approach is unfortunately too computationally time-consuming. In this study, we propose an acceptably fast simulation method that couples the contribution ratio of indoor climate (CRI), which is extracted from CFD results and indicates the individual impact of all heat factors, with the network model to implement an energy simulation that incorporates a temperature distribution. With the introduction of CRI, it is possible to achieve a precision as high as that of CFD and a calculation speed as fast as that of the network model. A case study simulating the thermal load of a single office room was carried out with the CRI-coupled method. The energy demand result calculated by CRI-coupled method was 15–20% lower than that of a non-coupled network simulation.

Highlights

► We develop a method to integrate spatial distributions into energy simulation (BES). ► We utilize the contribution ratio of indoor climate (CRI) extracted from CFD results. ► By the proposed method, the BES can be achieved at a much-reduced calculation load. ► A lower difference was obtained when comparing to a non-coupled network simulation.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

The mean radiant temperature is one of the six main variables responsible for the thermal sensation of the man exposed in a particular thermal environment (indoor and outdoor). Its measurement is not direct and is usually carried out by means of different methodologies and instruments whose general details and accuracy requirements are reported in the ISO Standard 7726. This paper deals with a critical review on the typical measurement methodologies combined with a comparative analysis of the metrological performances exhibited by the more common practice instruments on the market. To this purpose a special room-test has been designed aiming to reproduce the typical microclimatic conditions can be encountered in workplaces both in summer and in winter conditions. The effect of the measurement methodology and used instruments on the thermal comfort (global and local) and the thermal stress assessment has been finally discussed. Obtained results show that the use of different instruments consistent with ISO Standard 7726 requirements results in values of the mean radiant temperature compatible with each other, but the consequences on thermal environment assessment appear often ambiguous. Obtained results have focused the need for starting an in-depth discussion on the measurements’ protocols and the instruments leading to a possible reduction of the required accuracy levels reported in the ISO Standard 7726.

Highlights

► We have investigated the measurement methods of the mean radiant temperature. ► Measurements have been carried out in a test room reproducing moderate conditions. ► The method based on the angle factors is reliable. ► The method based on the net radiometer is often not compliant with other methods. ► The assessment of both global and local comfort can become quite random.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

As an advanced and efficient ventilation method, personalized ventilation (PV) has attracted more and more attentions. This paper investigates the pollutant transmission characteristics and personal exposure under the combination of two types of PV terminals and three kinds of typical background ventilation systems in an office with four work stations. Three kinds of cases are simulated and analyzed, including the most unfavorable condition, the most favorable condition and the ordinary condition. The results show that the interactions between PV and displacement ventilation (DV) or PV and under-floor air distribution (UFAD) are obviously stronger than that between PV and mixed ventilation (MV). Under a constant total ventilation rate, PV with a high flow rate may disrupt the characteristics of the background ventilation system and increase the personal exposure if comparing with the background ventilation alone. The advantage of PV depends on the proper combination of PV and its background ventilation system.

Highlights

► We simulate the transmission of pollutants in an office. ► We study the combinations of personalized ventilation (PV) and background ventilation systems. ► Personalized airflow may disturb the background airflow and increase personal exposure. ► The combination of PV and its background ventilation system should be properly designed.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

Energy-conscious design of gymnasium daylighting can contribute to significant energy savings and improve users' playing environment. The purpose of this research is to assess the relative impact of 22 different design factors on interior daylighting effects, and to formulate design recommendations for gymnasiums in mid-latitude area of China. Each factor with very high impact: dates, latitude, window position, glazing transmittance, building height, building depth and window area were simulated under the constraints of gymnasium illumination and illumination uniformity. The window area, which has the direct relationship with daylighting, is considered as the evaluation standard for the daylighting performance of other influence factors. A complex interdependence among these daylighting factors was found. By considering daylighting and energy-saving in combination, ‘Autumnal Equinox’ at 16:00 was identified as an appropriate daylighting design date and time. Side windows are not suitable for gymnasium daylighting except in designs where there is no seating. For small gymnasiums with no seats, the lighting performance of side-windows is most influenced by glazing transmittance, building height and depth. For all sizes of gymnasium skylights, the influential factors are glazing transmittance and building height. A simplified formula was obtained via linear regression, which enables architects to quickly calculate the required window area during the preliminary design phase.

Highlights

► 22 Design factors were extracted on interior daylighting effects. ► Seven factors with very high impacts were analyzed respectively. ► A simplified calculation of required window area was derived.

Available online 7 March 2013
Publication year: 2013
Source:Building and Environment

Occupant use of interior shading devices is one of the most influential factors in the admission of daylight into the buildings. Based on a number of observations, occupants don’t adjust shading devices frequently, and once lowered, the blinds are left in place for days or even weeks leading to reduced energy savings from daylight. Previous shade control behavior studies focus on environmental conditions such as transmitted vertical irradiance to predict the deployment of the shades; while there have been very few studies focusing on the factors that affect the raising of the interior shading devices by the occupants. This paper examines the effect of an interior lightshelf system on occupants’ use of blinds and electric lighting. The results suggest that in identical environmental conditions, occupants whose workstations were located within the lightshelf zone demonstrated a lower window occlusion than those who were located in the area with conventional windows. Additionally, occupants in the lightshelf zone used less electric lighting than those in regular window design area.

Highlights

► Shade raising events are very difficult to predict. ► Window shading design may have an effect on occupants’ use of venetian blinds. ► Subdivided windows with lightshelves can reduce lighting energy use in buildings.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

Intelligent buildings are beginning to utilize sensor networks for monitoring and protecting indoor air quality against contamination events. This paper presents a methodology for determining where to install such sensors. In particular, a multi-objective optimization problem is formulated for minimizing the sensor cost, the average and the worst-case impact damage corresponding to a set of contamination event scenarios. Each contamination scenario is comprised of parameters characterized by some given probability distribution. Based on these distributions, a set of representative contamination scenarios is constructed through grid and random sampling, and the overall impact of each scenario is computed, thus providing a solution to the sensor placement problem. The proposed methodology is illustrated by two case studies, a simple building with five rooms and a realistic building with 14 rooms.

Highlights

► Installation of air quality sensors in indoor building environments. ► Multi-objective optimization program that minimizes sensor cost and impact risk. ► Contamination scenarios construction based on probability distributions. ► Sensor placement optimization with respect to the contamination scenarios. ► Evaluation of methodology using building case studies.

May 2013
Publication year: 2013
Source:Building and Environment, Volume 63

Activated carbon (AC) has been widely used in indoor air quality (IAQ) control for removal of hazardous volatile organic compounds (VOCs). A detrimental effect of this adsorption technology is that bacteria multiplied on AC may deteriorate IAQ. In this paper, antibacterial AC nanocomposites with well-dispersed silver nanoparticles (Ag/ACs) were prepared by the attachment of Ag⁺ on the functionalized AC surface via ion–dipole interactions and the subsequent in-situ reduction of Ag⁺. The surfaces and microporous structures of the obtained Ag/ACs were analyzed by means of scan electron microscope (SEM) and pore size surface area analysis. Antibacterial tests were performed using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as model bacteria. Antibacterial activity against airborne bacteria and toluene adsorption capacity of AC nanocomposites were further evaluated. It was found that the introduction of Ag nanoparticles significantly improves antibacterial effect of AC but slightly reduces toluene adsorption ability. Ag/ACs can efficiently kill bacteria within 100 min without decreasing adsorption ability toward toluene.

Graphical abstract

Highlights

► Synthesis and characterization of Ag-coated activated carbon nanocomposites. ► Ag/ACs can efficiently kill bacteria within 100 min ► Ag/ACs remain high adsorption capacity toward VOCs.

Available online 13 March 2013
Publication year: 2013
Source:Building and Environment

This paper presents an exhaustive overview of the field studies carried out in the past few decades on human thermal comfort. To get a better grasp of patterns in observed data and to facilitate comparison across investigations, the thermal comfort field studies are grouped using the Köppen-Geiger climatic classification of their locations. Effects of relevant environmental, physiological, and other aspects that can have an effect on thermal comfort are reviewed and discussed. Field studies across the board show that people have considerable capacity to adapt to their surroundings provided they have sufficient adaptive opportunities. This observation holds good for both air-conditioned as well as free running buildings. However, studies show that conditioned spaces have narrower comfort zones compared to free running buildings. Across climatic zones, most popular means of adaptation are related to the modification of air movement and clothing. The ease, economy, and effectiveness (the 3 ‘E’s) of the adaptive opportunity play a major role in occupants’ adaptation of the surroundings. Studies show that individuals are likely to perceive the same thermal environment differently and environments lacking adaptive avenues normally receive poor comfort ratings. Studies also indicate that for adaptive comfort equations, the running mean temperature may be a better outdoor index compared to the monthly mean temperature.

Highlights

► Köppen’s climate classification is used to group thermal comfort field studies. ► Trends of comfort temperatures in different climate zones are examined. ► Evolution of field survey methodologies and questionnaires is discussed. ► Patterns and hindrances in use of adaptive opportunities are reviewed.

Available online 13 March 2013
Publication year: 2013
Source:Building and Environment

A field questionnaire survey was carried out simultaneously with weather measurements, in three urban areas in Athens, Greece, focusing on individual thermal sensation and its relationship with the environment in Mediterranean climates. Moreover thermal acceptability by means of thermal sensation votes was assessed based on Universal Thermal Climate Index (UTCI). People’s preference for warmer thermal conditions was identified. Women and individuals being at the interview site alone tended to be more sensitive to weather variations. Thermal sensation was defined by weather, personal and psychological factors. Air temperature and wind speed were the most important meteorological factors affecting thermal sensation while irradiation found to be a determining factor in improving thermal sensation in cool environments. The prognostic personal factors were clothing insulation and shading. The objective prevailing psychological factors were season and visit purpose. The estimated values of Universal Thermal Climate Index (UTCI) predicted fairly well thermal sensation votes in the case of the heat stress classes of UTCI assessment scale. The evaluation of thermal sensation is crucial in establishing successful health warning systems and designing public urban spaces that improve the living conditions of the population.

Highlights

► People prefer warmer thermal conditions showing increased tolerance to heat. ► Thermal sensation is determined by meteorological, personal, psychological factors. ► UTCI predicts well thermal sensation votes in the heat stress classes of the scale. ► Ordinal regression is appropriate for the prediction of thermal sensation

Available online 13 March 2013
Publication year: 2013
Source:Building and Environment

Aircraft cabins are designed with the aim of providing thermally comfortable conditions for the majority of passengers. To avoid the potential for dissatisfied customers, one focus for future design is on personalized climate zones.

In this context, the influence of individual preferences and expectations on comfort in an aircraft cabin was analysed. A study was conducted in an aircraft mock-up of a Dornier 728 using 60 subjects and a quasi-experimental design. Climate parameter sensations and personal characteristics were assessed via questionnaire; the cabin climate was measured by the use of various sensors. Two climate scenarios corresponding to cruising flight conditions (21.5 °C and 23 °C, volume flow of air 660 l/s, humidity approx. 18 %) were tested to analyse thermal comfort at the lower boundary of comfort temperatures in airplanes. Results confirm that the warmer climate was preferred to the colder one. Individual preferences – especially for warmth and air movement – had significant relationships with climate parameter perceptions and evaluations. Further, flight related expectations influenced the way in which the climate situation was rated: the higher the subjects’ expectations, the less comfortable the cabin climate was rated. The idea of implementing individual air conditioning is supported; practical implications of the findings are discussed.

Highlights

► Individual differences are taken into account for the analysis of thermal comfort. ► Preferences for certain climate parameters have an effect on climate sensations. ► Subjects’ expectations regarding the climate in aircrafts have an effect on comfort. ► The idea of personalized climate zones in aircraft passenger cabins is supported

Available online 13 March 2013
Publication year: 2013
Source:Building and Environment

Building construction in India is estimated to grow at a rate of 6.6% per year between 2005 and 2030 resulting in a continuous increase in demand for building materials. Fired clay bricks are the most widely-used walling materials in the country. However, over the past few decades, the development of other materials such as concrete blocks, fly ash bricks, stabilized mud blocks, etc., has created viable alternatives to bricks. There is limited understanding of the broader environmental consequences of these building materials addressing natural resource depletion, energy, environment and socio-economic impacts.

The main objective of this paper is to present a comprehensive assessment of materials used for wall construction by comparing one square meter of constructed wall for each of the materials. A composite Environmental Index was developed by weighting and aggregating normalized numerical scores of several parameters making use of a Multi-Criteria Decision Analysis (MCDA) framework. The Environmental Index was then ranked to determine walling systems that are best suited in the context of India.

Our analysis shows that wall assemblies that use non-fired products as masonry units are ranked higher compared to fired masonry unit wall assemblies. Clay fired masonry wall assemblies exhibit poorer environmental performance compared to non-fired masonry wall assemblies. When a more efficient form of construction such as the Rat-trap bond wall construction is considered, the environmental performance of clay fired brick walls is significantly improved.

Highlights

► We compare different building materials used for wall construction in India. ► We use an MCDA framework to derive an Environmental Index for each material. ► Non-fired materials are ranked higher compared to fired materials. ► Rat-trap bond construction technique improves the performance of fired materials.

Available online 13 March 2013
Publication year: 2013
Source:Building and Environment

Materials like building products or furnishing present in climatically controlled or uncontrolled indoor environments influence the indoor air quality (IAQ) significantly. In this study, the contribution of formaldehyde emissions from building materials and influences of adsorption/desorption behavior to indoor air pollution is investigated in a custom-made test house environment, located in a climate-controlled 48 m³ stainless-steel chamber. The complete test house study comprised three experimental cycles applying different types of ceiling tiles as target building materials. In each cycle one type of ceiling tile was used, while the housing construction and fittings were left unchanged. One cycle was divided into three steps to differentiate the contribution of each material to the overall IAQ: after the background monitoring of the empty housing frame (Step I), ceiling tiles were installed in the house and the air quality was monitored for one week (Step II). Finally, furniture and carpet were introduced into the house and the air was again monitored for one week (Step III). Additionally, gypsum boards and ceiling tiles were characterized by determination of their emission, diffusion and adsorption/desorption rates with regard to formaldehyde. It is the most important finding of this study that the resulting formaldehyde concentration does not simply result from additive emissions from the materials involved. In fact, it can only be explained accurately when taking into account multiple parameters.

Highlights

► Formaldehyde adsorption/desorption properties of ceiling tiles and gypsum boards. ► Factors influencing the overall formaldehyde concentration in indoor air. ► Formaldehyde diffusion in building materials. ► Effects of measures on fabrication of ceiling tiles with regard to emission reduction.