Paper Conference

Proceedings of Building Simulation 2017: 15th Conference of IBPSA


Glazing and Winter Comfort Part 1: An Accessible Web Tool for Early Design Decision-Making

M. Alejandra Menchaca-Brandan, Vera Baranova, Lynn Petermann, Stephanie Koltun-
Christopher Mackey Payette Associates, United States of America

Abstract: Of the factors that influence wintertime occupant thermal comfort, two are often of primary concern around cold windows: overall low mean radiant temperatures and localized downdraft currents. To prevent these from leading to a thermally uncomfortable environment in cold climates, the building industry has traditionally used perimeter heating – a system that is aesthetically unpleasing, costly to maintain and wasteful in its energy use. At present, quantifying discomfort from cold windows is either overly conservative, or relies on expensive and time-consuming simulation methods. Part 1 of this paper introduces the Glazing and Winter Comfort web tool, which identifies suitable glazing geometry and insulation performance criteria quickly and interactively to fully mitigate radiant and downdraft discomfort. Accordingly, this web tool aids designers in testing feasibility and iterating early in the design process, as well as informs the design team of critical thresholds during cost consideration exercises. Nomenclature Variable Description Units PMV Predicted Mean Vote (thermal sensation) PMV* Average of PMV over two heights (0.6m and 1.1m from the ground for seated occupants, 1.1m and 1.7m for standing occupants) PPDRad Predicted Percentage of Dissatisfied occupants associated to radiant discomfort PPDDraft Predicted Percentage of Dissatisfied occupants associated to downdraft discomfort MRT Mean radiant temperature K F View factor between occupant and surface ε Surface emissivity Tin Interior room temperature °C Tout Exterior room temperature °C vankle Downdraft speed at ankle height m/s x Occupant distance to façade m H Relevant downdraft height (Hwindow + Hsill) m Hwindow Height from bottom to top of window m Hsill Distance from floor to top of window sill m hc_in Convective heat transfer coefficient along the interior window surface W/m2K hr_in Radiative heat transfer coefficient along the interior window surface W/m2K Uwindow Window U-value W/m 2K
Pages: 2449 - 2456