Caroline Karmann

Caroline Karmann
École Polytechnique Fédérale de Lausanne | EPFL · Laboratory of Integrated Performance in Design (LIPID)

PhD

About

17
Publications
3,489
Reads
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168
Citations
Education
August 2012 - August 2017
University of California, Berkeley
Field of study
  • Architecture / Building Science

Publications

Publications (17)
Article
There is little knowledge from occupied buildings of the impact of radiant heating and cooling systems on indoor environmental quality aspects such as thermal comfort, indoor air quality, and acoustics. We present indoor environmental quality survey results from 3892 respondents in 60 office buildings located in North America; 34 of which used all-...
Article
Thermally activated building systems have the potential to achieve significant energy savings, yet, the exposed concrete may also create acoustical challenges due to the high reflectivity of the hard surface. Free-hanging acoustical clouds reduce the acoustical issues, but also the cooling capacity of a radiant chilled ceiling system. Fan-induced a...
Article
Radiant slab systems have the potential to achieve significant energy savings, yet, when applied in the ceiling (e.g., thermally activated building system) the exposed concrete may also create acoustical challenges due to the high reflectivity of the hard surface. Balancing all of the building indoor environmental quality factors is important in th...
Article
Hydronic radiant heating and cooling systems are considered as an energy efficient technology to condition buildings. We performed a literature review to assess if radiant systems provide better, equal or lower thermal comfort than all-air systems. We included only peer-reviewed articles and articles published in proceedings of scientific conferenc...
Article
Radiant cooling and heating systems have the potential for energy savings in buildings. Yet, depending on the world region, type of system, and conditioning mode, they have not been uniformly adopted. To address this disparity, we collected data on notable buildings using radiant systems with a focus on North America, type of system, conditioning m...
Article
Full-text available
Electrochromic (EC) glazing is increasingly employed in building façades to achieve better visual comfort for the occupants. EC glazing can modulate the light entering through the façade by varying the solar transmittance of the glass and therefore can work as a shading strategy to minimize solar heat gains or glare. However, it also alters the spe...
Article
Full-text available
Defining indoor environmental conditions that meet the needs and preferences of occupants in open space offices can be challenging since the same space might be occupied by people with different individual needs and preferences regarding what constitutes a comfortable work environment. This study presents outcomes of a set of longitudinal point-in-...
Article
Full-text available
The adaptable transmittance of electrochromic glazing allows to control the solar radiation entering buildings, yet the level of transmittance needed to protect from glare is still an unanswered question. To bridge this gap, this study evaluates the level of visible light transmittance (τv) required for blue-tinted low transmittance glazing to prev...
Conference Paper
Full-text available
Façades and light pattern composition have been shown to influence the spatial experience and physiological responses of humans [1,2]. The present study examines the effect of sunlight penetration and window size on fixations to the floor of the scene, and the relation between visual interest and fixations in an experiment using 360° scenes display...
Article
Full-text available
We performed a post-occupancy assessment based on 500 occupant surveys in eight buildings using embedded radiant heating and cooling systems. This study follows-up on a quantitative assessment of 60 office buildings that found radiant and all-air buildings have equal temperature and acoustic satisfaction with a tendency for increased temperature sa...
Conference Paper
A significant corpus of research has shown that occupant behaviour is a key factor of uncertainty when predicting building energy use. Building occupants affect energy use directly and indirectly by regulating their indoor environment according to their comfort criteria and a wide range of contextual, psychological or social factors. Increasing res...
Article
Radiant cooling and heating systems provide an opportunity to achieve significant energy savings, peak demand reduction, load shifting, and thermal comfort improvements compared to conventional all-air systems. As a result, application of these systems has increased in recent years, particularly in zero-net-energy (ZNE) and other advanced low-energ...
Technical Report
Full-text available
Radiant cooling and heating systems provide an opportunity to achieve significant energy savings, peak demand reduction, load shifting, and thermal comfort improvements compared to conventional all-air systems, and as a result, application of these systems has increased in recent years. However, due to the relatively new and unfamiliar nature of ra...
Technical Report
Full-text available
Radiant cooling and heating systems provide an opportunity to achieve significant energy savings, peak demand reduction, load shifting, and thermal comfort improvements compared to conventional all-air systems, and as a result, application of these systems has increased in recent years. However, due to the relatively new and unfamiliar nature of ra...
Article
Full-text available
In this paper we present the results from field studies of two low-energy office buildings in California, both using radiant slab ceiling systems (thermally activated building systems, TABS) for primary cooling and heating in the buildings. Both buildings are certified LEED Platinum and incorporate a wide range of energy efficient technologies and...

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Projects

Project (1)
Project
This project proposal is the continuation of the SNF project “Dynamic visual comfort metric - integrating dynamics of gaze pattern models and visual system behavior “, where we have investigated the influence of gaze in daylit spaces. The first project allowed us to develop a model that mimics people’s gaze behavior when exposed to potentially glary lighting environments and to develop and test the methodology and experimental setup necessary to conduct glare experiments in settings ranging from fully controlled to real-world conditions and with a novel focus on view direction. The proposed project extension aims to further this research path by also evaluating to what extent the visual system itself and the presence of high contrasts may influence the perception of glare: its main objective is to overcome the remaining limitations of our understanding of glare by investigating the interactions between glare and other visual factors such as visual interest, color, temperature and time of the day.Establishing reliable and objective measures of daylight comfort remains a crucial step to move towards optimal building design; yet despite numerous efforts in developing visual comfort models through human assessment studies, predicting visual comfort in indoor environments still poses important challenges. So far, existing visual comfort models only partially explain people´s visual comfort perception, and embed high uncertainties in their ability to anticipate the borderline between comfort and discomfort. The reasons why existing visual comfort models show high uncertainties in predicting user’s response are manifold. First of all, the models ignore the influence of the visual system (e.g., gaze reaction to the visual environment, contrast sensitivity, eye color). Second, commonly used metrics penalize a contrasted environment and neglect its positive impact on the users. Third, current glare models either concentrate on the saturation effect (e.g. DGP) or use contrast as measure for glare (e.g. DGI, UGP): as a result, they typically perform worse when both glare inducing factors occur simultaneously (e.g. DGP in dark and contrasted scenes or DGI in very bright low contrast scenes). And fourth, other potential influencing factors like temperature, color temperature or time of the day are not taken into account.Also, existing prediction models mostly concentrate on predicting discomfort, ignoring the positive aspects of contrasted light distributions. For example, for the same situation, a space’s occupants might perceive glare from the window, but would not describe the space as uncomfortable because they find it “exciting” or “stimulating”. As a consequence, people’s reactions remain difficult to predict with regards to the ways in which they may act upon their perception, such as through an interaction with shading devices and/or with electric lighting. This often leads to an energy demand higher than anticipated, given that daylight availability in the built environment may reduce needs for complementary electric lighting and/or for heating in the winter thanks to solar gains, but only if controlled, anticipated and managed adequately. The goal of this project continuation is to have a better, deeper and more objective understanding of the various factors impacting glare in order to improve our ability to predict and evaluate visual comfort in spaces and ultimately to improve design tools and the planning process of buildings. The work will be structured in 3 research tracks:-Track 1 (“Contrast”) will investigate in depth the influence of contrast on glare and consider its interplay with the positive contrast - it will be conducted in laboratory and in Virtual Reality environments. -Track 2 (“Interactions”) will examine the influence of the visual system, color, temperature and time of day - this track will be conducted only in laboratory environments.-Track 3 (“Validation and tool”) will validate the gaze model developed in the first (concluded) SNF project, as well as the findings from Track 1 and Track 2 by means of user assessments in real office spaces (POE-studies). Existing glare prediction models will be extended to account for the influencing factors that will have been found statistically significant in Tracks 1 and 2. The project outcome will significantly advance and broaden the scientific knowledge in the field of visual comfort. Besides this important short-term impact, on the long run the results will improve the design process by the use of more reliable metrics. And finally, users, employers and owners will benefit from higher comfort and productivity as well as optimized building performance and reduced energy demands. (http://p3.snf.ch/Project-182151)