Indoor gaseous air pollutants determinants in office buildings—The OFFICAIR project

The aim of this study was to identify determinants of aldehyde and volatile organic compound (VOC) indoor air concentrations in a sample of more than 140 office rooms, in the framework of the European OFFICAIR research project. A large field campaign was performed, which included (a) the air sampling of aldehydes and VOCs in 37 newly built or recently retrofitted office buildings across 8 European countries in summer and winter and (b) the collection of information on building and offices’ characteristics using checklists. Linear mixed models for repeated measurements were applied to identify the main factors affecting the measured concentrations of selected indoor air pollutants (IAPs). Several associations between aldehydes and VOCs concentrations and buildings’ structural characteristic or occupants’ activity patterns were identified. The aldehyde and VOC determinants in office buildings include building and furnishing materials, indoor climate characteristics (room temperature and relative humidity), the use of consumer products (eg, cleaning and personal care products, office equipment), as well as the presence of outdoor sources in the proximity of the buildings (ie, vehicular traffic). Results also showed that determinants of indoor air concentrations varied considerably among different type of pollutants.     

Nutzerzufriedenheit und Komfort am Arbeitsplatz – Ergebnisse einer Feldstudie in Bürogebäuden

Thermal comfort and satisfaction at workplaces – a field study in office buildings. By applying multivariate analysis to survey data of a field study in 17 buildings, several correlations between different parameters with regard to satisfaction at workplaces could be found and validated. One important result was that the individual satisfaction parameters were independent. A significant difference between winter and summer votes on the satisfaction with the indoor temperature could be shown; the dissatisfaction at neutral thermal sensation was considerably higher in summer. In total, only 30% of the occupants were very satisfied or satisfied with the temperature at their workplace in summer and winter. The perceived effectiveness of attempted temperature changes proofed to be the dominant parameter for the satisfaction with the indoor temperature. By weighting individual satisfaction parameters a matrix could be generated which provides a straight‐forward assessment of building performance by showing the optimisation potential for each parameter and the necessity to act for the building manager. The conclusion with regard to building design is that small office rooms with individual control of the indoor environment perform best in terms of acceptance by occupants.     

Using field measurements of desktop illuminance in European offices to investigate its dependence on outdoor conditions and its effect on occupant satisfaction,and the use of lights and blinds

Adequate indoor illuminance is accepted as one important determinant of conditions for comfort and productivity in offices. This paper uses the results of field surveys in 26 offices in five European countries (France, Greece, Portugal, Sweden and the UK) to investigate what illuminance levels are actually achieved on office desks, what light level is considered ‘best’ by occupants, and how this is affected by outdoor sky conditions and illuminance. The paper also explores how blinds and lights are used by occupants to modify light levels at their desks. The office workers show a remarkable degree of adaptation to different light intensities. They use controls to modify the light level at their desks to almost the same mean level irrespective of the sky conditions outside. There is a small but significant effect of lighting on self-reported productivity which seems to be higher when offices are daylit.     

Thermischer Komfort – die extraphysikalischen Aspekte

Extraphysical parameters of thermal comfort. Standards define thermal comfort as a function of physical and thermophysiological parameters. From investigations of building related symptoms it is well known that satisfaction with the indoor environment also interacts with extraphysical parameters. Thus, data of 1,497 office workers investigated in phase II of the ProKlimA study have been analysed by multiple logistic regression to find associations between thermal sensation or comfort and potential non‐environmental variables. The results show diverse effects: While thermal sensation seems almost independent from non‐environmental impacts, thermal comfort and satisfaction with the indoor temperature are significantly associated with building characteristics, demographic and job related variables. From these significant and partly strong interactions we conclude, in case of analyses and assessment of complaints about thermal discomfort relevant non environmental impact factors should be considered.     

Effect of renovating an office building on occupants' comfort and health

An intervention study was performed in a mechanically ventilated office building in which there were severe indoor climate complaints among the occupants. In one part of the building a new heating and ventilation strategy was implemented by renovating the HVAC system, and a carpet was replaced with a low-emitting vinyl floor material; the other part of the building was kept unchanged, serving as a control. A comprehensive indoor climate investigation was performed before and after the intervention. Over a 2-week period, the occupants completed a daily questionnaire regarding their comfort and health. Physiological examinations of eyes, nose and lungs were performed on each occupant. Physical, chemical and sensory measurements were performed before and after the intervention. The renewal of the flooring material was performed after a sensory test of alternative solutions in the laboratory. Before the floor material was installed in the office building, a full-scale exposure experiment was performed in the laboratory. The new ventilation strategy and renovation of the HVAC system were selected on the basis of laboratory experiments on a full-scale mock-up of a cellular office. The severity of occupants' environmental perceptions and symptoms was significantly reduced by the intervention.     

Associations of perceived indoor environmental quality with stress in the workplace

Indoor environmental quality (IEQ) is a general indicator of the quality of conditions inside a building. We investigated associations of perceived IEQ including air quality, thermal comfort, noise, and light quality with stress at work and the extent to which workplace location modifies these associations. We recruited 464 full-time workers from four companies in Singapore. Data on socio-demographic characteristics, lifestyle/health-related factors, and workplace factors were collected through self-administered questionnaires. Perceived IEQ satisfaction scores of all four factors were collected using the validated OFFICAIR questionnaire. We fitted a logistic regression model to assess associations between each perceived IEQ score and stress at work, adjusting for potential confounders. The odds ratio for stress at work associated with a 1-unit increase in perceived air quality score was 0.88 (0.82-0.94), 0.89 (0.82-0.97) for thermal comfort, 0.93 (0.87-0.98) for noise, and 0.88 (0.82-0.94) for light quality. Significant associations were found in office and control rooms for all four perceived IEQ, except for thermal comfort in office rooms. Higher satisfaction levels of perceived air quality, thermal comfort, noise, and lighting, were significantly associated with a reduction in stress at work. Our findings could potentially provide a useful tool for environmental health impact assessment for buildings.     

Perceived control in indoor environments: a conceptual approach

Building automation systems provide the potential to optimize the energy consumption of buildings as well as to detect failures in the operation of buildings. The system comprising building form–HVAC–building automation–user is becoming more complex. Providing the occupants with control over the indoor environment is widely accepted for its positive effect on their satisfaction. This paper explores what the term ‘perceived control’ means conceptually and draws implications for its application to the design and management of buildings. Personality- and environmental-psychology emphasize the importance of personal control to humans. The adaptive model of thermal comfort, findings from post-occupancy evaluations and surveys in real buildings also indicate the importance of high levels of perceived control. These models and findings exist in parallel and have not yet been interconnected and translated into models for the built environment. A new conceptual approach to explain perceived control is proposed. Satisfaction with the indoor environment occurs not only when ‘comfort’ is provided but also immediately after a successful control action, even if homeostasis has not yet been achieved (pleasure). Giving control to occupants can result in higher levels of satisfaction.     

Impact of psycho-social factors on perception of the indoor air environment studies in 12 office buildings

The main function of a mechanically ventilated office building is to provide a healthy and comfortable working environment for occupants, while maintaining minimum energy consumption. Twelve mechanically ventilated buildings were selected. They varied greatly in surface area, number of floors, occupant density, and building use. The indoor air quality, thermal comfort, energy consumption, and perception of occupants were investigated in these buildings. A total of 877 subjects participated in the questionnaire survey during the hot summer months of June, July, and August, and during the cold winter months of January, February, and March. The questions included in the questionnaire dealt with health, environmental sensitivity, work area satisfaction, personal control of the workstations environment, and job satisfaction. Measured parameters concerning the quality of indoor air included ventilation rate, concentration of TVOC, CO₂, CO, RH, and formaldehyde. The thermal comfort parameters included room air, mean radiant, plane radiant asymmetry, and dew point temperatures, as well as air velocity and turbulence intensity. Monthly energy consumption data was also gathered for each building. Ventilation performance, in terms of air flow rate and indoor air quality, was compared with the ASHRAE Standard 62-89R (Ventilation for Acceptable Indoor Air Quality. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [1]). The measured and calculated thermal environmental results were also compared with the ASHRAE Standard 55-92 (Thermal Environmental Conditions for Human Occupancy. Atlanta: American Society of Heating, Refrigerating, and Air Conditioning Engineers, Inc. U.S.A. [2]). CO₂ and CO levels satisfied the recommended limits. The outdoor airflow rate was half that recommended in only one building. The formaldehyde and TVOC levels were moderately higher than suggested comfort levels. However, more than 56% of the occupants rated dissatisfaction with the indoor air quality. Only 63% of the indoor climatic observations fell within the ASHRAE Standard 55-92 summer comfort zone; 27% in the winter. However, only 69% of those surveyed agreed with the comfort zones. More symptoms were reported by workers who perceived IAQ to be poor. Positive relationships were observed between the job satisfaction and satisfaction with office air quality, ventilation, work area temperature, and ratings of work area environment. However, job dissatisfaction did not correlate with symptom reports. The occupants were more dissatisfied with IAQ when they preferred more air movement. In other words, the higher the perceived air movement, the greater the satisfaction with IAQ.     

Neutral temperature in subtropical climates—A field survey in air-conditioned offices

The thermal environment for air-conditioned offices in subtropical climates is examined from the prospect of maintaining an optimum operative temperature for the occupants. In this study, the optimum neutral temperature is evaluated from 422 occupants’ responses towards the perceiving thermal environment in 61 air-conditioned offices and 186 complaints of thermal discomfort in an air-conditioned office building on an electronic questionnaire, using a semantic differential evaluation scale and a dichotomous assessment scale. In particular, physical parameters for the thermal comfort study were measured by an indoor environmental quality (IEQ) logger, and the operative temperature was correlated with the occupants’ thermal responses. The probability of accepting an operative temperature for the thermal comfort of the occupants was correlated with logistic regression curves; the optimum operative temperature was derived in order to maximize the probability of thermal comfort expressed by the occupants. The results showed that the thermal neutral temperatures for air-conditioned offices in subtropical climates were 23.6 and 21.4 °C in summer and winter, respectively. The preferred thermal environment in Hong Kong should be slightly cool, corresponding to about 1 °C below the neutral temperature, in order to satisfy most of the occupants in the office space.     

Comfort of workers in office buildings: The European HOPE project

Previous studies have shown that building, social and personal factors can influence one’s perceived health and comfort. The aim of the underlying study was to get a better understanding of the relationships between these factors and perceived comfort. Self-administered questionnaires from 5732 respondents in 59 office buildings and building-specific data from the European Health Optimisation Protocol for Energy-efficient buildings (HOPE) study were used. Principal Component Analysis (PCA), reliability analyses, and linear regression analysis were performed. The outcome showed that perceived comfort is strongly influenced by several personal, social and building factors and that their relationships are complex. Results showed that perceived comfort is much more than the average of perceived indoor air quality, noise, lighting and thermal comfort responses. Perceived comfort is a phenomenon that deserves more research.     

Perceived Air Quality,Sick Building Syndrome (SBS) Symptoms and Productivity in an Office with Two Different Pollution Loads

Abstract Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in an existing office in which the air pollution level could be modified by introducing or removing a pollution source. This reversible intervention allowed the space to be classified as either non-low-polluting or low-polluting, as specified in the new European design criteria for the indoor environment CEN CR 1752 (1998). The pollution source was a 20-year-old used carpet which was introduced on a rack behind a screen so that it was invisible to the occupants. Five groups of six female subjects each were exposed to the conditions in the office twice, once with the pollution source present and once with the pollution source absent, each exposure being 265 min in the afternoon, one group at a time. They assessed the perceived air quality and SBS symptoms while performing simulated office work. The subject-rated acceptability of the perceived air quality in the office corresponded to 22% dissatisfied when the pollution source was present, and to 15% dissatisfied when the pollution source was absent. In the former condition there was a significantly increased prevalence of headaches (P= 0.04) and significantly lower levels of reported effort (P=0.02) during the text typing and calculation tasks, both of which required a sustained level of concentration. In the text typing task, subjects worked significantly more slowly when the pollution source was present in the office (P=0.003), typing 6.5% less text than when the pollution source was absent from the office. Reducing the pollution load on indoor air proved to be an effective means of improving the comfort, health and productivity of building occupants.     

The effect of structures on indoor humidity--possibility to improve comfort and perceived air quality

The research presented in this paper shows that moisture transfer between indoor air and hygroscopic building structures can generally improve indoor humidity conditions. This is important because the literature shows that indoor humidity has a significant effect on occupant comfort, perceived air quality (PAQ), occupant health, building durability, material emissions, and energy consumption. Therefore, it appears possible to improve the quality of life of occupants when appropriately applying hygroscopic wood-based materials. The paper concentrates on the numerical investigation of a bedroom in a wooden building located in four European countries (Finland, Belgium, Germany, and Italy). The results show that moisture transfer between indoor air and the hygroscopic structure significantly reduces the peak indoor humidity. Based on correlations from the literature, which quantify the effect of temperature and humidity on comfort and PAQ for sedentary adults, hygroscopic structures can improve indoor comfort and air quality. In all the investigated climates, it is possible to improve the indoor conditions such that, as many as 10 more people of 100 are satisfied with the thermal comfort conditions (warm respiratory comfort) at the end of occupation. Similarly, the percent dissatisfied with PAQ can be 25% lower in the morning when permeable and hygroscopic structures are applied.     

Indoor environment quality and upgrading of European office buildings

Indoor environmental quality (IEQ) is an important quality aspect of office buildings, which is acknowledged in a new European methodology and software for office building refurbishment (TOBUS). In TOBUS, an inventory of complaints from occupants about IEQ is made as well as an inventory of characteristics of building and HVAC-system. Based on relations between characteristics of buildings and systems and the use of the building, different possible causes for the problems can be identified and possible actions for improvement can be selected. A relation scheme is provided with relations between objects and types, complaints of occupants in an office building, possible causes of those complaints and actions that should take away those complaints. Furthermore, a relation scheme is provided with causes and actions that cannot be related to an object. A procedure to qualify and quantify the IEQ performance of a building is given. This article describes the results of the field investigations in 12 European buildings focused on the IEQ part. Discussions and conclusions from this field study with respect to IEQ and with respect to the methods and procedures used are also presented.     

Ventilation,indoor environment quality and climate—comparison of European and Singapore office buildings

Indoor environment quality audits were performed in six European countries and in Singapore using the same methodology. Five to eight office buildings were audited in each country. The audits included airflow rate measurements, energy audit, indoor air quality (VOC₁ CO₂, dust concentrations), and questionnaires to occupants. Questions to occupants addressed their health, their comfort and well-being, as well as their perception of their environment. This paper compares the results obtained from these audits, with particular attention to the effects of ventilation or air conditioning systems and climate.

The number of building related symptoms is, on the average, significantly smaller in the buildings audited in Singapore than in Europe. One of the reasons may be the non-smoking policy common in Singapore. It is also once more observed that buildings are often over-warmed in cold climates and overcooled in warm climates. Surprising, but not new, is that there are no correlations between specific air flow rates and perceived air quality or health, as long as airflow rates are within accepted standards.     

Categories of indoor environmental quality and building energy demand for heating and cooling

Maintaining suitable indoor climate conditions is a need for the occupants’ well being, while requiring very strictly thermal comfort conditions and very high levels of indoor air quality in buildings represents also a high expense of energy, with its consequence in terms of environmental impact and cost. In fact, it is well known that the indoor environmental quality (IEQ), considering both thermal and indoor air quality aspects, has a primary impact not only on the perceived human comfort, but also on the building energy consumption. This issue is clearly expressed by the European Energy Performance of Buildings Directive 2002/92/EC, together with the most recent 2010/31/EU, which underlines that the expression of a judgment about the energy consumption of a building should be always joint with the corresponding indoor environmental quality level required by occupants. To this aim, the concept of indoor environment categories has been introduced in the EN 15251 standard. These categories range from I to III, where category I refers to the highest level of indoor climate requirement. In the challenge of reducing the environmental impact for air conditioning in buildings, it is essential that IEQ requirements are relaxed in order to widen the variations of the temperature ranges and ventilation air flow rates. In this paper, by means of building energy simulation, the heating and cooling energy demand are calculated for a mechanically controlled office building where different indoor environmental quality levels are required, ranging from category I to category III of EN 15251. The building is located in different European cities (Moscow, Torino and Athens), characterized by significantly different wheatear conditions. The mutual relation between heating and cooling energy demand and the required levels of IEQ is highlighted. The simulations are performed on a typical office room which is adopted as a reference in validation tests of the European Standard EN 15265 to validate calculation procedures of energy use for space heating and cooling.     

Association of subjective health symptoms with indoor air quality in European office buildings: The OFFICAIR project

The aim of this study was to explore the association between the building-related occupants’ reported health symptoms and the indoor pollutant concentrations in a sample of 148 office rooms, within the framework of the European OFFICAIR research project. A large field campaign was performed in 37 office buildings among eight countries, which included (a) 5-day air sampling of volatile organic compounds (VOCs), aldehydes, ozone, and NO₂ (b) collection of information from 1299 participants regarding their personal characteristics and health perception at workplace using online questionnaires. Stepwise and multilevel logistic regressions were applied to investigate associations between health symptoms and pollutant concentrations considering personal characteristics as confounders. Occupants of offices with higher pollutant concentrations were more likely to report health symptoms. Among the studied VOCs, xylenes were associated with general (such as headache and tiredness) and skin symptoms, ethylbenzene with eye irritation and respiratory symptoms, a-pinene with respiratory and heart symptoms, d-limonene with general symptoms, and styrene with skin symptoms. Among aldehydes, formaldehyde was associated with respiratory and general symptoms, acrolein with respiratory symptoms, propionaldehyde with respiratory, general, and heart symptoms, and hexanal with general SBS. Ozone was associated with almost all symptom groups.     

Benefits and costs of improved IEQ in U.S. offices

This study estimates some of the benefits and costs of implementing scenarios that improve indoor environmental quality (IEQ) in the stock of U.S. office buildings. The scenarios include increasing ventilation rates when they are below 10 or 15 l/s per person, adding outdoor air economizers and controls when absent, eliminating winter indoor temperatures >23°C, and reducing dampness and mold problems. The estimated benefits of the scenarios analyzed are substantial in magnitude, including increased work performance, reduced Sick Building Syndrome symptoms, reduced absence, and improved thermal comfort for millions of office workers. The combined potential annual economic benefit of a set of nonoverlapping scenarios is approximately $20 billion. While the quantitative estimates have a high uncertainty, the opportunity for substantial benefits is clear. Some IEQ improvement measures will save energy while improving health or productivity, and implementing these measures should be the highest priority. PRACTICAL IMPLICATIONS: Owners, designers, and operators of office buildings have an opportunity to improve IEQ, health, work performance, and comfort of building occupants and to obtain economic benefits by improving IEQ. These benefits can be achieved with simultaneous energy savings or with only small increases in energy costs.     

Particulate Matter Intervention Study: A Causal Factor of Building-Related Symptoms in an Older Building

Abstract Five floors of a 20-year old 6-story office building were investigated using an integrated step-by-step investigation strategy. This involved a walkthrough inspection, an occupant questionnaire, and targeted environmental monitoring of indoor air quality and comfort parameters. The initial questionnaire survey revealed a high occurrence of building-related symptoms. The walkthrough inspection and environmental monitoring identified deposits of surface dust (indoor surface pollution – ISP) on carpets and hard surfaces, and elevated levels of carbon dioxide and respirable suspended particulate matter (RSP) throughout the building. An intervention study (blinded to the occupants) was targeted at reducing ISP levels by replacing normal carpet cleaning practices with higher performance vacuum cleaners and improved cleaning practices. The intervention reduced ISP levels and significantly lowered RSP concentrations by approx. 80% from initial values and against control floors. A follow-up SBS questionnaire revealed significant reductions in all but two of the symptoms. The most significant reductions occurred with symptoms of eye irritation, throat irritation, dry unproductive cough, and nose irritation. The study showed that in older buildings with poor ventilation, a build-up of ISP, and elevated RSP levels, using higher performance carpet cleaning practices can reduce RSP to acceptable levels and can reduce SBS symptoms.     

Bayesian adaptive comfort temperature (BACT) of air-conditioning system in subtropical climate

Indoor thermal climate is an important issue affecting the health and productivity of building occupants. In the designing of commercial air-conditioning systems, it is believed that the conventional fixed temperature set point concept is limited because indoor comfort temperature depends on the business culture, such as the nature of activities and dress code of occupants, etc. Researchers have been interested in investigating adaptive temperature control for a realistic in-situ control of comfort. Unfortunately, those studies put great emphasis on energy saving opportunities and sometimes might result in thermal discomfort to individuals. This study argues that complaints of thermal discomfort from individuals, despite representing only a small portion of the population, should not be ignored and can be used to determine the temperature setting for a population in air-conditioned environment. In particular, findings of a new notion of Bayesian adaptive comfort temperature (BACT) in air-conditioned buildings in a humid and subtropical climate like Hong Kong are reported, and the adaptive interface relationship between occupants’ complaints of thermal discomfort and indoor air temperature is determined. This BACT algorithm is intended to optimise the acceptance of thermal comfort, as determined by physical measurements and subjective surveys.     

Thermal comfort: use of controls in naturally ventilated buildings

A field study of the thermal comfort of workers in natural ventilated office buildings in Oxford and Aberdeen, UK, was carried out which included information about use of building controls. The data were analysed to explore that what effect the outdoor temperature has on the indoor temperature and how this is affected by occupants’ use of environmental controls during the peak summer (June–August). The proportion of subjects using a control was related to indoor and outdoor temperatures to demonstrate the size of the effect. The results suggest that the use of controls is also related to thermal sensation and their appropriate use is a significant part of adaptive behaviour to modify the indoor thermal conditions. The results make it possible to predict the effect of temperature on the ventilation rate in naturally ventilated buildings.