An area of our research with broad reach is our investigation of glazing and thermal comfort in the winter. Our team sought to understand, as early as schematic design, which façade properties negatively or positively impact occupant comfort. When it comes to glazing in the winter time, perimeter heat is the most common solution provided to avoid any potential discomfort. However, there is a constant desire to eliminate the need to use this technology, given that it represents an added first cost to projects, requires constant maintenance and degrades the thermal performance of the glazed facade. In our project work, we have discovered that it is often less expensive to specify triple glazing because it enables us to eliminate the need for perimeter heating. We set out to identify the “tipping point” where this phenomenon occurs.
Because of the many factors that glazing has on occupant comfort such as feeling cold due to radiant losses to the glass or due to cold downdraft, this led us to develop the free and publicly available Glazing and Winter Comfort Tool. The tool, developed by an interdisciplinary team of building scientists, designers and software developers, offers designers a simplified method for analyzing the comfort of their glazing design. The result is a powerful yet simple tool that is easily understood and used by the design community.
The team reviewed and evaluated the relevance of current research to relate existing thermal comfort models to parameters known in early design, such as façade geometry, building material properties, outdoor climate and other criteria. While this collaboration provided the team with tools that could analyze one specific design at a time, the introduction of software development ensured that the research reached a larger audience through the online interface. In addition to the research and design necessary to build the tool, we also ran two rounds of testing to ensure a high quality user experience.
Since the tool was published in September 2016, we have an average of 650 pageviews per month and we have been told by dozens of firms that they have utilized our tool. We have employed this analysis on at least a dozen projects, enabling us to eliminate perimeter heat in many of them.
Here is an example of how the tool can be used during the design process of your next project:
Case Study: Finding the Right Geometry
The design of a high performance building often involves setting a target glazing ratio. However, for the same glazing ratio, the possible glazing scenarios can lead to very different thermal comfort conditions.
This case study considers a project under design with a goal of 50% window-to-wall ratio, where the team wanted to avoid the use of perimeter heat in the offices.
Three very different glazing are considered: Short punched windows with a 3’ sill (Case 1) are compared to tall windows without a sill (Case 2) and to ribbon windows with the same 3’ sill (Case 3). For an occupant sitting 3’ from the window, only Case 3 provides comfort levels below the goal (<10% PPD-Radiant and <20% PPD-Downdraft).
In Cases 1 and 2 downdraft (triangle icon) will be too strong to ensure occupant comfort without the use of perimeter heating.
In the video below, learn how we inputted the information to calculate the results and how to use other features such as exporting the results into a PDF or sharing via an URL.
Glazing and Winter Comfort Tool 2.0
Glazing and Winter Comfort Tool
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Glazing and Winter Comfort FAQs
Thermal Comfort and Glazing Design