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.     

Determination of type I phase matching angles and conversion efficiency in KTP

Measurements of the conversion efficiency of second-harmonic generation in KTP (KTiOPO(4)) by the use of type I phase matching for different fundamental wavelengths of a mode-locked picosecond Ti:sapphire laser are presented. The observed phase matching angles are in agreement with the calculated phase matching curves. At a fundamental wavelength of 834 nm and an intensity of 100 MW/cm(2) the conversion efficiency is 4% at maximum, and the corresponding effective nonlinear coefficient d(eff) is equal to 0.32 pm/V. The experimental values of d(eff) are related to d(11) (= 0.46 pm/V) of quartz and are in line with the predictions.     

European Indoor Air Quality Audit Project in 56 Office Buildings

Abstract A European project started at the end of 1992, in which, in addition to current methods, trained sensory panels were used to investigate office buildings all over Europe. The main aim of this EC-Audit was to develop assessment procedures and guidance on ventilation and source control, to help optimize energy use in buildings while assuring good indoor air quality. In each of nine countries, six or more office buildings were selected. Measurements were performed at five selected locations in each building. The buildings were studied while normally occupied and ventilated to identify the pollution sources in the spaces and to quantify the total pollution load caused by the occupants and their activities, as well as the ventilation systems. The investigation included physical and chemical measurements, assessment of the perceived air quality in the spaces by a trained sensory panel, and measurement of the outdoor air supply to the spaces. A questionnaire for evaluating retrospective and immediate symptoms and perceptions was given to the occupants of the buildings. The building characteristics were described by use of a check-list. The annual energy consumption of the buildings and the weather conditions were registered. This paper presents results and conclusions of the audit in 56 buildings in Europe. However, the analysis and discussions of the results are a summary of the work done, and are focused mainly on comparison between sensory assessments and the other measurements performed. Furthermore, this paper brings the results of the study based on a two-factor analysis. A paper dealing with results on a multifactorial analysis is in preparation.     

Addition of Olfs from Different Pollution Sources,determined by a Trained Panel

The purpose of this study was to predict how indoor air is perceived when polluted by different materials simultaneously. A panel of five trained judges was exposed to air polluted by each of 11 different single pollution sources. The panel was also exposed to 13 pair combinations of these single pollution sources and to one combination of five sources. The pollution sources comprised typical indoor building materials, materials from ventilation systems and other frequently occurring indoor pollution sources. The results indicate that the total sensory pollution load in a space may, as a first approximation, be predkted by simple addition of the olf values of the single sources.     

Very short far-infrared pulses from optically pumped CH3OH/D, CH3F, and HCOOH lasers using an EQ-switched CO2laser as a pump source

Very short far-infrared (FIR) pulses were generated from optically pumped CH3F, CH3OH/D, and HCOOH lasers using aQ- switched, current pulsed (200 mA, 100 μs), low pressure (20 torr) CO2laser as a pump source. Values of 20 ns for the rise time and 50 ns for the decay time of the FIR pulses have been observed. The dependence of the FIR pulse shape parameters, i.e., rise time, decay time, and pulse buildup time, on the width of the pump pulse and the pressure of the molecular gas have been investigated experimentally. Due to the regular pulse shape, high repetition rate (350 Hz), high peak power (≳1 W), and broad spectral range (lambda = 100-500 mum), the pulses are very useful for purposes of solid-state and molecular time resolved spectroscopy.     

Operation of a double heterojunction GaAs/AlGaAs injection laser with a p-type active layer in a strong magnetic field

Measurements of the energy shift of the laser emission and the threshold current of a double heterojunction GaAs/AlGaAs injection laser with a p-type active layer as a function of the magnetic field up to25 Tand atT = 6K and 40 K are presented. A simple expression is derived for calculation of the maximum of the gain curve, which coincides with the energy of the laser emission as a function of the magnetic field and the electronic scattering time. From the experimentally observed shift of the laser emission and the calculated maximum of the gain curve as a function of the magnetic field values for the carrier density at threshold, and for the electronic scattering time in the active layer at both temperatures have been obtained.     

Towards an integrative approach of improving indoor air quality

There seems to be a discrepancy between current Indoor Air Quality standards and end-users wishes and demands. Indoor air quality can be approached from three points of view: the human, the indoor air of the space and the sources contributing to indoor air pollution. Standards currently in use mainly address the indoor air of the space. “Other or additional” recommendations and guidelines are required to improve indoor air quality. Even though we do not fully understand the mechanisms behind the physical, chemical, physiological and psychological processes, it is still possible to identify the different ways to be taken regulatory, politically–socially (awareness), technically (process and product) and scientifically. Besides the fact that there is an urgent need to involve medicine and neuro-psychology in research to investigate the mechanisms behind dose-response, health effects and interactions between and with the other factors and parameters of the indoor environment and the human body and mind, a holistic approach is required including the sources, the air and last but not least the human beings (occupants) themselves. This paper mainly focuses on the European situation.     

A Large Conductivity Change in 2DES on Liquid 4He Under CR Conditions

We present the first magneto-conductivity measurements on a two-dimensional electron system on liquid ⁴He under cyclotron resonance conditions. The measurements are performed in the temperature region above 1K, where the scattering with helium-gas atoms is the dominant scattering mechanism. We observe a large change in the magnetoconductivity at the resonant magnetic field. When increasing the power of the radiation, we observe subsequently a decrease and an increase in the normalised inverse conductivity We think this power dependence can be understood in terms of hot electron effects.