David P Wyon

Technical University of Denmark | DTU · International Centre for Indoor Environment and Energy

Humans emit carbon dioxide (CO2) as a product of their metabolism. No measurements of CO2 emission rates (CERs) of elderly sleeping people have yet been reported. This study performed such measurements and examined the possible mechanisms impacting CERs. Sixteen participants (8 males) aged ≥65 years old slept alone for a whole night under each of t...

Ten healthy young adults slept one by one in a specially designed and constructed sleep capsule located in a climate chamber at two temperatures (24 and 28 °C) and two ventilation rates that ensured that the resulting CO2 concentrations were 800 and 1700 ppm. Subjectively rated sleep quality was reduced at 28 °C and reduced ventilation, while sleep...

Sleep is essential for the health of elderly people, but few studies have made connection between their sleep quality and their bedroom environment. This study performed field measurements in Shanghai, China, to investigate the bedroom thermal environment and ventilation and their associations with the sleep quality of elderly subjects in summer. F...

This study managed to create thermal comfort conditions at three temperatures (24°C‐T24, 26°C‐T26, and 28°C‐T28) by adjusting clothing and air velocity. Thirty‐six subjects (18 males and 18 females) were exposed to each of the three conditions for 4.5 h in a design balanced for order of presentation of conditions. During each exposure, they rated t...

Three conditions were established to investigate the effects of ventilation and related ventilation noise on sleep quality: No mechanical ventilation/low noise (A); Mechanical ventilation /low noise (B); Mechanical ventilation/high noise (C). The interventions were achieved by idling a mechanical ventilation system or operating it in two different...

This study investigated whether adjusting clothing to remain in neutral thermal comfort at moderately elevated temperature is capable of avoiding negative effects on perceived acute subclinical health symptoms, comfort and cognitive performance. Two temperatures were examined: 23°C and 27°C. Twelve subjects were able to remain thermally comfortable...

Sensory input from the skin appears to be of crucial importance in the regulation of sleep but there has been limited research on human skin temperature during sleep. The present study was undertaken to validate calculation of the mean skin temperature (MST) of sleeping subjects from measurements at only three locations: forehead, chest, and foot,...

A two‐week long intervention study was performed in two classrooms in an elementary school in Costa Rica. Split‐cooling air conditioning (AC) units were installed in both classrooms. During the first week, the air temperature was reduced in one classroom while in the other (placebo) classroom the fans were operated but no cooling was provided. Duri...

A field‐intervention study was carried out in 106 households in Sweden. Without informing the householders, a retrofitted heat pump controller was twice disabled for one week at a time over a 4‐week period during the heating season, using a single‐blind cross‐over design with two pseudo‐randomly selected groups of householders, each experiencing di...

Is sleep becoming so much scarcer than ever before because people do not realize the importance of sleep for health and well-being? All over the world, digital communications now mean that contact with work continues after hours and during weekends and that “friends” are no longer just the people we meet regularly, but the many more we contact regu...

The effects of bedroom air quality on sleep and next-day performance were examined in two field intervention experiments in single-occupancy student dormitory rooms. The occupants, half of them women, could adjust an electric heater to maintain thermal comfort but they experienced two bedroom ventilation conditions, each maintained for one week, in...

Both sleep and good indoor air quality are generally considered to be important for human health and well-being. In the present study, sleep quality and next-day performance were measured in identical single-occupancy dormitory rooms located in a quiet area North of Copenhagen. The 16 international students participating as subjects, half of them w...

The effect of air quality on sleep was examined for occupants of 14 identical single-occupancy dormitory rooms. The subjects, half women, were exposed to two conditions (open/closed window), each for one week, resulting in night-time average CO2 levels of 660 and 2585 ppm, and air temperatures of 24.7 and 23.9°C, respectively. Sleep was assessed fr...

Thank you for giving us an opportunity to reply to the letter from Leyten and Kurvers (2013) concerning our recent paper on the effects of thermal discomfort in an office (Lan et al. 2011). Our experiment does not show which of several possibly driving factors caused our subjects to perform simulated office work about 10% more slowly when they felt...

As experienced researchers in the effects of thermal comfort and indoor air quality on performance, we are often asked to give our best estimate of how, and to what extent, performance is affected by different aspects of indoor climate. This article provides a brief summary of our personal opinions, in the form of answers to 40 frequently asked que...

This paper is an overall summary of research by the authors on how classroom conditions affect the performance of schoolwork by children, motivated by the fact that the thermal and air quality conditions in school classrooms are now almost universally worse than the relevant standards and building codes stipulate that they should be. This is someti...

Abstract The effects of thermal discomfort on health and human performance were investigated in an office, in an attempt to elucidate the physiological mechanisms involved. Twelve subjects (six men and six women) performed neurobehavioral tests and tasks typical of office work while thermally neutral (at 22°C) and while warm (at 30°C). Multiple phy...

Experiments were carried out in a simulated aircraft cabin with 21 seats installed in a climate chamber, to determine the extent to which passengers' perception of cabin air quality is affected by air temperature. The temperature inside the cabin was set at three different levels, 20.6, 23.3 and 26.1°C. A total of 68 subjects were exposed to each o...

When dealing with indoor air pollution problems caused by substances known to be toxic, field experimentation has been virtually ruled out by ethical considerations. Even the omission of remedial measures for experimental purposes can be said to be unethical. What remains is the descriptive approach, in which the occurrence of toxic substances and...

In 8 climate chamber experiments at air temperatures ranging from 25 to 45°C, a total of 24 subjects dressed in summer clothing were each exposed to 4 different water feed temperatures in a heated/cooled seat, ranging from cool to warm. In one simulated summer series subjects were preconditioned to be hot, while in another series they were thermall...

Unlabelled: Experiments were carried out in a three-row, 21-seat section of a simulated aircraft cabin installed in a climate chamber to evaluate the extent to which passengers' perception of cabin air quality is affected by the operation of a gas-phase adsorption (GPA) purification unit. A total of 68 subjects, divided into four groups of 17 subj...

Two independent field intervention experiments involving a total of about 190 pupils were carried out in winter and early spring of 2005 in five pairs of mechanically ventilated classrooms that received 100% outdoor air. Each pair of classrooms was located in a different school. Electrostatic air cleaners were installed in classrooms and either ope...

The experiment presented in this report was performed in a simulated aircraft cabin to evaluate the air cleaning effects of two air purification devices that used photocatalytic oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjective human assessments were used for the evaluation. Comparisons were made...

Ninety-nine young-adult subjects of both genders were randomly assigned to four groups. One group performed simulated office work for two hours in a set of poor environmental conditions, with overhead fluorescent lighting, recorded traffic noise from a busy street, 27°C (80.6°F) operative temperature, supply air polluted by emissions from linoleum,...

A human subject experiment was performed to examine the effect of office noise and temperature on human perception, comfort and office work performance. The experiment concerned offices of two different sizes with three different acoustical treatments. An open-plan office environment was simulated by playing office sounds through a surround-sound s...

The thermal environment in a full-scale 21-seat section of an aircraft cabin installed in a climate chamber was investigated. Fourteen heated cylinders and two thermal manikins were used to simulate the heat load, buoyancy flow and flow obstruction from passengers in the cabin. Measurements were carried out at cabin air temperatures of 20.6°C, 23.3...

In 11 climate chamber experiments at air temperatures ranging from 15 to 45 degrees C, a total of 24 subjects, dressed in appropriate clothing for entering a vehicle at these temperatures, were each exposed to four different seat temperatures, ranging from cool to warm. In one simulated summer series, subjects were preconditioned to be too hot, whi...

Abstract Abstract A 21-seat section of an aircraft cabin with realistic pollution sources was built inside a climate chamber capable of providing fresh outside air at very low humidity. Maintaining a constant 200 l/s rate of total air supply, i.e. recirculated and make-up air, to the cabin, experiments simulating 7-h transatlantic flights were car...

Two independent field intervention experiments were carried out in school classrooms in late summer (in 2004 and 2005). The air temperature was manipulated by either operating or idling split cooling units installed for the purpose. In one of these experiments, the outdoor air supply rate was also manipulated. The conditions were established for on...

Two independent field intervention experiments were carried out in mechanically ventilated classrooms receiving 100% outdoor air. Outdoor air supply rate and filter condition were manipulated to modify indoor air quality, and the performance of schoolwork was measured.The conditions were established for one week at a time in a blind crossover desig...

Four different air purification conditions were established in a simulated 3-row 21-seat section of an aircraft cabin: no air purifier; a photocatalytic oxidation unit with an adsorptive prefilter; a second photocatalytic unit with an adsorptive prefilter; and a two-stage sorption-based air filter (gas-phase absorption and adsorption). The air puri...

Ozone concentrations were measured concurrently inside a simulated aircraft cabin and in the airstream providing ventilation air to the cabin. Ozone decay rates were also measured after cessation of ozone injection into the supply airstream. By systematically varying the presence or absence of people, soiled T-shirts, aircraft seats and a used HEPA...

The perception of locally applied airflow was studied with tropical subjects who had become passively acclimatized to hot conditions in the course of their day-to-day life. During the experiments, 24 subjects (male and female) performed normal office work in a room equipped with six workstations. They were exposed to local airflow from the front an...

Poor indoor air quality and high indoor air temperatures have been shown to negatively affect adults' performance of office work, but little information exists on whether they also have negative effects on the performance of schoolwork by children. This was the conclusion of a recent wide-ranging and authoritative review of published research that...

In a 3-row, 21-seat section of a simulated aircraft cabin that had been installed in a climate chamber, 4 groups of 17 subjects, acting as passengers and crew, took part in simulated 11-hour flights. Each group experienced 4 conditions in balanced order, defined by two outside air supply rates (2.4 and 3.3 L/s per person), with and without a Gas-Ph...

Thirty subjects (17 female) were exposed for five hours in a climate chamber at 22°C (71.6°F) to clean air at 5%, 15%, 25%, and 35% RH. A comparable group was similarly exposed to air polluted by carpet and linoleum to the 35% RH condition and to 18°C, 22°C, and 26°C (64.4°F, 71.6°F, and 78.8°F) at an absolute humidity equal to 15% RH at 22°C (71.6...

Human perception of local air movement under steady state conditions in the Tropics has been relatively little reported. This study explores the thermal and air movement perception of a group of Tropically acclimatized subjects (24 people) after 90 minutes of facial exposure to local air movement. The subjects were exposed to several predefined loc...

Principal component analysis was carried out to reduce dimensionality of subjective responses from surveys conducted in three call centers, in which 300 call center operators participated. Results consistently revealed five clusters of variables (also termed as subjective factors): 1) intensity of neurobehavioral-related symptoms and self-assessed...

The concept of personalized ventilation (PV) is at the cutting edge of technological development in the area of air conditioning and is fundamentally aimed at improving ventilation in the immediate breathing zones of occupants in the built environment. While the current state-of-the-art PV systems make this possible for seated individuals within th...

Experiments were carried out in a simulated section of an aircraft cabin with 21 seats installed in a climate chamber, to determine the extent to which passengers' perception of cabin air quality is affected by air temperature. The temperature inside the cabin was set at three differ-ent levels, 20.6°C, 23.3°C and 26.1°C (69°F, 74°F and 79°F), whil...

The experiment presented in this report was performed in a simulated aircraft cabin to evaluate the air cleaning effects of two air purification devices using Photocatalytic Oxidation (PCO) technology. Objective physical, chemical and physiological measurements and subjective human assessments were used for the evaluation. Comparisons were made bet...

We used proton-transfer-reaction mass spectrometry (PTR-MS) to examine the products formed when ozone reacted with the materials in a simulated aircraft cabin, including a loaded high-efficiency particulate air (HEPA) filter in the return air system. Four conditions were examined: cabin (baseline), cabin plus ozone, cabin plus soiled T-shirts (surr...

The thermal environment in a 21-seat simulated section of an aircraft cabin installed in a climate chamber was investigated. Using two thermal manikins and fourteen heated cylin- ders to represent passengers, measurements were carried out at cabin temperatures of 20.6°C, 23.3°C and 26.1°C (69°F, 74°F and 79°F), while maintaining a total air supply...

A field intervention experiment was conducted in two classes of 10-year-old children. Average air temperatures were reduced from 23.6 o C to 20 o C and outdoor air supply rates were increased from 5.2 to 9.6 L/s per person in a 2x2 crossover design, each condition lasting a week. Tasks representing 8 different aspects of school work, from reading t...

Low humidity in the aircraft cabin environment has been identified as a possible cause of symptoms experienced during long flights. A mock-up of a 21-seat section of an aircraft cabin with realistic pollution sources was built inside a climate chamber, capable of providing fresh outside air at very low humidity. Experiments simulating 7-hour transa...

A re-analysis of two independent laboratory studies was made in which a total of 60 female subjects had been exposed for several hours to 6 different air quality conditions in groups of 6 people at a time. The subjects performed typical office tasks at their own pace during exposures. Measured carbon dioxide (CO2) concentrations and outdoor air sup...

100 drivers aged 23-65, 53 male and 47 female, were recruited to drive an apparently unmodified passenger car for one hour in city traffic. They were randomly assigned either to a control condition, or to ionised air containing 20 000-30 000 negative ions/ml, but were unaware of the presence of an ioniser in the vehicle. A computer initiated unprep...

Unlabelled: A 2 x 2 replicated field intervention experiment was conducted in a call-center providing a telephone directory service: outdoor air supply rate was adjusted to be 8% or 80% of the total airflow of 430 l/s (3.5 /h) and the supply air filters were either new or had been in place for 6 months. One of these independent variables was chang...

Unlabelled: Three air temperatures (22/26/30 degrees C) and two acoustic conditions-quiet (35 dBA) or open-plan office noise (55 dBA)-were established in an office. Thirty subjects aged 18-29 years (16 male), clothed for thermal neutrality at 22 degrees C, performed simulated office work for 3 h under all six conditions. Many more (68% vs. 4%) wer...

Unlabelled: Perceived air quality (PAQ), sick building syndrome (SBS) symptoms and performance of office work were studied in a real office space at three levels of air temperature and humidity and two levels of ventilation rate (20 degrees C/40%, 23 degrees C/50%, 26 degrees C/60% RH at 10 l s(-1) p(-1) outside air, and 20 degrees C/40% RH at 3.5...

Unlabelled: The main justification for ventilation has historically been to create a healthy indoor environment. Ventilation removes air pollutants originating inside the building, including bio-effluents. The outdoor air supply rate that has been found by experience to provide subjectively acceptable indoor air quality and to prevent the accumula...

The following values have no corresponding Zotero field: CY - Singapore

Abstract The present paper shows that introducing or removing the same pollution source in an office in two independent investigations, one in Denmark and one in Sweden, using similar experimental methodology, resulted in similar and repeatable effects on subjective assessments of perceived air quality, intensity of sick building syndrome symptoms...

Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in a normally furnished office space (108 m3) ventilated with an outdoor airflow of 3, 10 or 30 L/s per person, corresponding to an air change rate of 0.6, 2 or 6 h-1. The temperature of 22 degrees C, the relative humidity of 40% and all other environmental p...

The impact of electrostatic precipitation as a useful form of particulate filtration in the breathing zone is investigated in an intervention study in an air-conditioned commercial office in central London. Surface dust deposition and airborne dust levels are measured in the open plan zones of two floors--a control floor and a floor where the inter...

In laboratory experiments, we investigated two task/ambient conditioning systems with air supplied from desk-mounted air outlets to efficiently ventilate the breathing zone of heated manikins seated at desks. In most experiments, the task conditioning systems provided outside air while a conventional ventilation system provided additional space coo...

The results of three independent studies involving 90 subjects, and using similar procedures and blind exposures have shown that increasing air quality (by decreasing the pollution load or by increasing the ventilation rate, with otherwise constant indoor climate conditions) can improve the performance of simulated office work (text typing, additio...

The following values have no corresponding Zotero field: CY - Espoo, Finland

This study tested questionnaires using visual analogue scales (VAS) in a cleaning intervention study and attempted to find a simple way of analyzing the replies to the questionnaires. A VAS questionnaire made up of 26 questions was developed and marked once a week for 28 weeks by the room occupants in 3 buildings. A total of 1248 questionnaires was...

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...

Education is about general principles and is intended to equip the student for the future. It should therefore always include a historical perspective, as those who do not learn from past mistakes are bound to repeat them in the future. Training is about passing on current experience and deals with empirical facts rather than theoretical principles...

In order to examine the effect of energy intake at breakfast on school performance the same morning, the parents of ten parallel school classes of 10-year-old school children at five different schools were persuaded to alter their child's breakfast regimen at home over a period of 4 successive days. A total of 195 families were provided with standa...

In order to examine the effect of energy intake at breakfast on school performance the same morning, the parents of ten parallel school classes of 10-year-old school children at five different schools were persuaded to alter their child's breakfast regimen at home over a period of 4 successive days, A total of 195 families were provided with standa...

A total of 83 drivers, 51 males and 32 females, aged 25-65, were recruited to drive an apparently unmodified passenger car for 1 h over at least four laps of a predetermined route on public roads, which included seven sets of traffic lights and sections limited to 50, 70, 90 and 110 km/h. They were randomly assigned to one of two thermal conditions...

When 207 subjects wearing their own clothing were randomly assigned to 9 conditions, consisting of 3 levels of vertical thermal gradient (nominally 0, 2 & 4 K/m), and 3 levels of estimated whole-body heat loss (40, 48 & 56 W/m2 as measured on a similarly-clothed and seated thermal manikin, corresponding to warm, neutral and cool conditions respecti...

It is commonly recommended that children should receive about 25% of their daily nutritional requirements at breakfast. In this study two test breakfasts were provided at home by parents, in random order for 4 successive days, to 195 10-year old school children, in 7 mixed-gender Swedish schools. The test breakfasts were either a Complete Cereal Br...

The case for using symptom intensity feedback testing (SIFT) procedures to determine which of the available practical measures will be effective in improving the design or management of a problem building is presented. Instantaneous symptom intensity is estimated by the occupants using visual analogue scales which have been validated against object...

A thermal manikin with constant skin temperature and a wind-chill tunnel with constant air temperatures and wind speeds were used to measure whole-body heat loss for seven ensembles chosen to represent the full range of civilian outdoor clothing in use for everyday, nonsporting wear. Equations fitting the data with correlation coefficients exceedin...

Thermal manikins are a fairly standard tool in environmental ergonomics. As they can provide a rapid, accurate, and reproducible simulation of the physical processes of dry heat loss to the environment, their main application is in the study of neutral or cold conditions at relatively low activity levels. Thermal manikins provide a good estimate of...