Recent cedr_cbe_es items

View Access Index: The effects of geometric variables of window views on occupants’ satisfaction

Tue, 14 Mar 2023 00:00:00 +0000

View Access Index: The effects of geometric variables of window views on occupants’ satisfaction

The effect of thermochromic windows on visual performance and sustained attention

Wed, 15 Dec 2021 00:00:00 +0000

Thermochromic windows have been widely studied as a technology that can potentially offer increases in energy conservation and provide a desirable luminous environment inside buildings. However, there has been little attention placed on how the tinted states of thermochromic glazing influence occupant behaviour and visual perception. An experiment under controlled conditions was designed to test the influence of different thermochromic tint states on human response. By using a controllable artificial window, five typical luminous conditions were set up, including clear (no tint) and two different levels of blue and bronze tint states, respectively, which produced different room colour temperatures. Thirty-one subjects were recruited who completed three visual tasks, including a visual acuity and a colour naming tasks using the coloured Landolt ring chart and a sustained attention test using the d2 test. Subjective assessments were also collected using questionnaires. Statistical...

The impact of a view from a window on thermal comfort, emotion, and cognitive performance

Thu, 9 Apr 2020 00:00:00 +0000

Visual connection to nature has been demonstrated to have a positive impact on attention restoration, stress reduction, and overall health and well-being. Inside buildings, windows are the primary means of providing a connection to the outdoors, and nature views even through a window may have similar effects on the occupants. Given that humans recognize environments through multi-sensory integration, a window view may also affect occupants’ thermal perception. We assessed the influence of having a window with a view on thermal and emotional responses as well as on cognitive performance. We conducted a randomized crossover laboratory experiment with 86 participants, in spaces with and without windows. The chamber kept the air and window surface temperature at 28 °C, a slightly warm condition. The outcome measures consisted of subjective evaluations (e.g., thermal perception, emotion), skin temperature measurements and cognitive performance tests. In the space with versus without...

Thermal comfort in naturally ventilated buildings: revisions to ASHRAE Standard 55

Wed, 12 Feb 2020 00:00:00 +0000

Recently accepted revisions to ASHRAE Standard 55—thermal environmental conditions for human occupancy, include a new adaptive comfort standard (ACS) that allows warmer indoor temperatures for naturally ventilated buildings during summer and in warmer climate zones. The ACS is based on the analysis of 21,000 sets of raw data compiled from field studies in 160 buildings located on four continents in varied climatic zones. This paper summarizes this earlier adaptive comfort research, presents some of its findings for naturally ventilated buildings, and discusses the process of getting the ACS incorporated into Standard 55. We suggest ways the ACS could be used for the design, operation, or evaluation of buildings, and for research applications. We also use GIS mapping techniques to examine the energy-savings potential of the ACS on a regional scale across the US. Finally, we discuss related new directions for researchers and practitioners involved in the design of buildings and...

A simulation-based design analysis for the assessment of indoor comfort under the effect of solar radiation

Thu, 11 Apr 2019 00:00:00 +0000

One of the drivers of sustainable design is to maximize daylight across the floor plan in order to decrease electric energy consumption and create more productive and healthy working spaces. However, uncontrolled incoming solar radiation can lead to significant visual and thermal comfort issues. In particular, solar radiation landing on occupants can create thermal discomfort that the HVAC system cannot compensate for, thereby causing intolerable conditions for users close to the façade. We aim to present a new climate-based annual framework, based on ASHRAE 55 appendix C (2017), to assess radiant discomfort across a space due to direct solar radiation. The framework is calculated using the hourly effective radiant field (ERF) and delta Mean Radiant Temperature (ΔMRT) across the indoor space. The Radiance-based framework coupled with the proposed Annual Radiation Discomfort metric (ARD) provides designers a robust method to assess the performance of complex fenestration systems...

Ventilation, thermal and luminous autonomy metrics for an integrated design process

Wed, 3 Oct 2018 00:00:00 +0000

This paper proposes and evaluates an integrated workflow that simultaneously uses ventilation, thermal, and luminous autonomy for the assessment of passive design strategies, introducing a potential way to integrate these three metrics in the design process. We developed a new metric, ventilation autonomy, and assessed the advantages and limitations of applying the three autonomy metrics with building performance simulations in two climates. We developed a novel visualization to display the hourly and yearly environmental autonomy values. The results show that when we consider the three metrics together, designers may have contradicting design directions if trying to both mitigate the solar radiation and to utilize natural ventilation. The visualizations that categorize nine combinations of thermal and visual comfort along with ventilation autonomy are effective in showing the trade-offs among ventilation, thermal, and visual performance.

Performance, prediction, optimization, and user behavior of night ventilation

Tue, 10 Apr 2018 00:00:00 +0000

Previous studies have demonstrated a potential reduction in cooling load and improvement in comfort from the implementation of night ventilation. This paper describes the performance, in terms of indoor environmental conditions, of three buildings from both the U.S. and India that use night ventilation as their primary cooling method. The research methods used the following approach: (1) Assess the cooling strategy in relation to the adaptive comfort model; (2) Develop a hybrid model, using both first principle equations and the collected data, to predict the instantaneous air and mass temperatures within each building and use the model to assess performance of the cooling strategy; (3) Determine an optimized ventilation control strategy for each building to minimize energy and maintain comfortable temperatures. (4) Develop a statistical model using collected data to predict the window opening pattern for occupants of a building using natural night ventilation. The study yielded...

Building envelope impact on human performance and well-being: experimental study on view clarity

Tue, 10 Oct 2017 00:00:00 +0000

The goal of this project was to assess the visual effect of selected aspects of the building envelope on human performance and perception, first broadly, and then focused on view clarity. The initial literature review examined human factors that could be explicitly considered in building envelope design, operation and current daylight metrics. We found that debate remains on the practical applicability of these metrics, and gaps exist between daylight and other building envelope-related aspects such as view. Following the literature review, we narrowed down our research question to experimentally investigate the visual performance of fabric shading systems and electrochromic windows under both diffuse and direct sunlight conditions, and develop a view clarity rating method. We introduce and show results from an experimental study done at Lawrence Berkeley National Laboratory’s Windows Testbeds. We tested High Dynamic Range (HDR) photography techniques to capture the different...

Balancing Thermal and Luminous Autonomy in the Assessment of Building Performance

Tue, 13 Jun 2017 00:00:00 +0000

This paper proposes and evaluates a novel approach that simultaneously uses thermal and luminous autonomy for the assessment of human-centered passive design strategies, introducing a potential way to integrate these two metrics in the design process. In this study, we assessed the advantages and limitations of applying the two autonomy metrics with energy and lighting simulations in two climates. We developed a novel visualization to display the hourly thermal and luminous autonomy values for an entire year. The results showed that when we consider the two metrics together, designers may have contradicting design directions to mitigate the solar radiation; for example, the space is overly cool, but it is overlit at the same time, or the space is overly warm, but the daylight metrics predicts it is underlit. The visualization categorizes thermal and visual comfort in nine combinations allowing the designers to understand the trade-off relationships between thermal and visual aspects...

Mixed Mode Simulation Tools

Tue, 2 Dec 2014 00:00:00 +0000

Mixed Mode Simulation Tools

The adaptive model of thermal comfort and energy conservation in the built environment