Documenting view clarity metrics for product standards and certification systems.
Status: Current
Funding Sources: ASHRAE CBE Industry Partners
Project Objective
This project will develop standardized view clarity metrics to predict how single- or multi-layer window systems, having distinct physical and optical properties, affect occupants’ ability to see outdoors clearly. We will also propose a product rating and certification scheme that benchmarks current and future fenestration solutions against the proposed standardized view clarity metrics.
Project Results
Our team will deliver view clarity metrics designed to predict how clearly occupants can see through a wide range of fenestration materials and their combinations. We expect these metrics to serve two key purposes: First, as design guidance to help practitioners balance between low-clarity conditions, where privacy, glare control, and energy savings are prioritized, and high-clarity conditions that support the well-documented benefits of a clear visual connection to the outdoors. Second, as a product rating scheme that provides a unified method to incorporate the “view” perspective into material specifications. We plan to have these findings reported in peer-reviewed journals, and included in the fenestration chapter of the ASHRAE Handbook of Fundamentals and related documents.
Significance to Industry
A clear visual connection to the outdoors offers benefits that have been documented in previous research, including higher property values and improved mental, physical, and emotional health. To fully realize these benefits, it is essential to understand how modern fenestration systems affect occupants’ ability to clearly see outside. Three primary factors define a good window view: content, access, and clarity. Among these, view clarity, the degree to which occupants can clearly see outdoor objects, varies greatly depending on the selection and design of window and shading products and materials. While these systems are commonly used to manage glare, daylight, privacy, and energy use, our industry still lacks reliable metrics to quantify their impact on view clarity.
Research Approach
Building on our prior work developing the Window View Quality Index and studies related to view clarity, we propose two primary components to develop view clarity metrics: Design of experimental facility and protocol and conduct experiments involving human subject experiments.
We will begin by planning the experimental facility and protocol. Our group plans to build three test cells: one equipped with clear glazing, one with electrochromic glass, and one with fritted or coated glass. We will make each cell to include six fabric roller blinds and four Venetian blinds. We will install visual targets placed up to 20 ft (6.1 m) from the exterior glazing to measure visual performance. We will also define the experimental protocol, with the dataset expected to include three main components: (1) fenestration properties, based on both manufacturer specifications and lab measurements; (2) participants’ clarity assessment results; and (3) quantified visual environment data. Read more details about the research methods.
Second, we will conduct experiments involving a total of 50 participants. In each session, we plan to guide three participants through the three test cells, with the sequence of cell visits randomized for each participant. We will also randomly select three blinds from the light-colored fabrics and three from the dark-colored fabrics for each cell. Inside each cell, we will randomize both the order of the three main conditions, glazing only, glazing with fabric blinds, and glazing with Venetian blinds, and the sequence of materials within each condition. For each session, we will use a spectroradiometer to measure the visual environment for each condition. Additional details about the methods