11:15am - 11:18am
Comparative field tests of an electrochromic shading device - thermal and visual comfort
Sintef AS, Norway
Windows, generally, have higher heat losses than the opaque parts of a building envelope due to inferior thermal insulation levels. Windows should provide light and possibly a view towards the outdoors to guarantee comfort and wellbeing for the occupants. Electrochromic devices (EC), also known as Smart Windows, are amongst the most promising technologies on the market that can join these two apparently contradictory qualities. Like all shading systems, they contribute to increase the internal comfort and the energy efficiency of the building, but unlike traditional systems they are integrated in the glazing unit and they can have a better impact on the visual comfort of the occupants.
A comparative field test of EC windows performance was realised in the ZEB Test Cell Laboratory in Trondheim, Norway. The facility is made of two identical test rooms suspended in a guard room with the façade exposed to outdoor weather.
For this research, one of the two identical rooms of the facility was equipped with EC devices, the other with a traditional insulated glazing unit (IGU) and a screen as external solar shading device.
Three different automatic control strategies were tested in this experiment. Each control was based on a different measured parameter, namely the internal operative temperature, the internal illuminance level and the external solar radiation impinging the façade.
The EC device demonstrated a good impact on the thermal and visual comfort when compared to a traditional IGU without moveable shading and a traditional IGU with an external screen. The automatic control based on the impinging solar radiation on the façade demonstrated to be the most suitable in the climatic conditions were the experiment was carried out.
11:18am - 11:21am
Analyzing Solar Light Effects on Indoor Thermal Comfort in Near-Window Zones
Department of Architectural Engineering, The Pennsylvania State University, United States of America
The interaction among the spectral characteristics of solar radiation, windows, and human skins may affect indoor thermal comfort in the near-window zones. For analyzing such shortwave solar effects through windows on indoor thermal comfort, a more explicit method taking spectral features into account is indispensable. We first built a new calculation methodology, called spectral integral method, upon a previous work that was mainly used to transfer the shortwave solar effect into the equivalent longwave effect to calculate indoor thermal comfort with the predicted mean vote. Compared with the previous ones centered on the constant and simplified radiometric quantities, the uniqueness of this method is to provide the underlying radiometric calculation with the detailed and precise spectral contents and their variations of radiation sources, mediums, and receivers details. Subsequently, we analyzed the effects on indoor thermal comfort by the solar light transmitted through several representative glazing systems that have different spectral characteristics. We adopted solar irradiance data from 8:00 to 18:00 with an interval of one hour in Denver, Colorado in a case study to verify the necessity of the spectral integral method relative to the constant method and also quantify the effects of transmitted solar light on indoor thermal comfort. This work lays the foundation to analyze the interaction between the window features and temporal-dependent solar radiation and its impacts on indoor thermal comfort.
11:21am - 11:24am
Evaluation of methods for determining thermal properties of window systems
Instytut Techniki Budowlanej / Building Research Institut, Poland
The aim of the work is an experimental evaluation of methods for determining thermal properties of modern design window systems. The paper will present the test results of thermal properties of aluminum windows obtained in laboratory tests applying the Hot-Box method according to the EN 12567-1 and EN ISO 8990 standards and calculation methods according to EN 10077-1 and EN 10077-2 standards, where the treatment of cavities using both the radiosity and single equivalent thermal conductivity methods are applied. On the basis of the test results and numerical calculations, thermal parameters, such as the frame thermal transmittance Uf, the linear thermal transmittance ψ at the joint of the frame and glazing unit and the window thermal transmittance for an aluminum window system will be discussed. The knowledge of the possibilities and limitations of the applied research and calculation methods is important due to their application to determine the thermal properties of energy-saving solutions in the window systems.
11:24am - 11:27am
Evaluation of the performance of glazed balconies based on temperature monitoring
Lublin University of Technology, Poland
Glazed balconies in dwellings located in multi-family buildings are attractive architectural elements providing thermal and acoustic protection of adjacent heated rooms. They influence the energy balance of the flats thanks to the temperature rise caused by solar gains in unheated sunspaces. The potential benefits, however, may differ depending on the inhabitants’ behaviour.
To evaluate these effects, internal temperature in buildings located in Zamość (a city in the eastern part of Poland) was monitored at the turn of the years 2017 and 2018. The temperature was recorded in half-an-hour intervals with the use of iButton sensors located in flats and sunspaces. Three dwellings with the same orientation were included in the research – two (with glazed balconies) differing by the area of the living space, the number of the inhabitants, and their behaviour, and one with an open balcony, used for comparison.
Thanks to the collected data, it was possible to check the effects of the glazed space on the heat losses during the heating season and thermal comfort during summer. The analyses also included the calculation of the temperature reduction factor, expressing the relative temperature rise in the solar space above the outside air temperature.
Air temperature in the sunspace was usually higher than the temperature of the air outside and quite well correlated with its course. In the dwellings with glazed balconies, despite the same construction and orientation, internal temperatures in the living space differed due to the inhabitant’s preferences as to the heating and venting intensity. These issues also had some impact on the differences in the values of the temperature correction factor and thermal comfort in summer.
11:27am - 11:30am
Experiences using EN 17037 in evaluation of daylighting of dwellings in Slovakia
Slovak University of Technology, Faculty of Civil Engineering, Radlinskeho 11, 810 05, Bratislava, Slovakia
The daylighting of indoor spaces depends particularly on the urban and architectural parameters of the building environment. The new standard EN 17037, Daylight in Buildings, has brought several changes and uncertainties in design process of daylighting for buildings. The submitted paper is focused on analysis of the philosophy of the new standard criteria in relation to the daylighting of dwellings along with the criteria that have been used in Central European countries for decades. EN 17037 does not distinguish between differences in the functional use of indoor spaces in terms of daylight provision. The new European standard requires at the half of subjectively determined reference plane to achieve the same value of illumination for half of daylight hours per year for any occupied room. The EN standard does not sufficiently respect the specifics of daylighting of dwellings.
11:30am - 11:33am
In situ Ug-value measurement on three different glazing types
Technical University of Darmstadt, Germany
This study presents in situ monitoring data of three different glazing systems over a period of one year. An insulated glass unit (IGU), a Vacuum Insulated Glass hybrid unit (VIG-hybrid) and an opaque architectural insulation module (AIM) were monitored under the equivalent environmental condition in this study. Different issues were observed and analyzed. It was found that the Ug-value cited by the manufacturers agrees with the Ug-values derived from the measured data, to within less than 5 % for the IGU and the VIG-hybrid. The consistency of the Ug-value of each glazing types one year after the start of monitoring was validated for similar environmental conditions. Depending on the magnitude of the resistance to heat flow, an increasing Ug-value was observed for a higher temperature difference between the inside and outside environments. The effect is much more significant for the glazing type with the largest Ug-value (IGU) and less significant for the glazing types with a high thermal resistance (VIG-hybrid, AIM).