Interested in including a skylight in your next building design, but not quite sure if the benefits outweigh the costs? Looking for ways to improve the design of the skylights you currently manufacture? SkyVision predicts skylight performance for any given day and for various types of skylights. The software is a useful tool whether you're a building designer or architect, skylight manufacturer or educator

SkyVision is an easy-to-use, Microsoft Windows^TM-based computer program developed by the National Research Council Canada in partnership with Natural Resources Canada and Public Works and Government Services Canada. The software calculates for a given design day, the overall optical characteristics (transmittance, absorptance, reflectance and Solar Heat Gain Coefficient) of various skylight types, performance indicators of skylight/room interfaces (well efficiency and coefficient of utilization), indoor daylight availability (daylight factor and illuminance) and lighting energy savings. It is intended for use by skylight and curb manufacturers, building designers, architects, engineers, fenestration councils, and research institutions.

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Features

Detailed calculation of skylight optical characteristics and indoor illuminance
State-of-the-art glazing optics calculation models.
Ray-tracing-based modelling to compute the skylight optical and daylighting performance.
Side-by-side comparison of design performance.
Results in graphical or tabular formats that can be used as inputs for third-party software such as building thermal simulation software.
Choice of two unit systems: English (IP), or International (SI).
Attached glass product database to build skylight products.
Climate file database to simulate scenarios with real, dynamic sky conditions.
On-line help.
Automatic lighting and shading control effects.

Calculation Engine

SkyVision's calculation engine is composed of four sets of modules: glazing optics modules that compute the optical characteristics of a composite glazing pane (substrate with/without coating) and glazing assembly (set of composite panes separated by an air/gas space) at a given incidence angle; skylight optics modules that compute the overall skylight optical characteristics; daylighting modules that compute indoor illuminance distribution and related quantities; and sky models that compute sky luminance distribution. These modules feature the following:

The monolithic model is currently used to compute the optical properties of a composite pane at oblique incidence angles for each light polarization component.
Ray-tracing based models to compute the optical characteristics of representative skylight shapes, and a newly-developed concept of the Shape Parameter is used to compute the optical characteristics of skylight shapes other than representatives.
The newly-developed zonal model, in which the space below the skylight is split into a number of vertical, three/four-surface (floor, walls, ceiling and opening) zones, is used to calculate the diffuse and inter-reflected components of surface light fluxes. Ray-tracing based method is used to compute the direct components of surface light fluxes.
CIE/IES standard sky condition and the climate-based (Perez et al.) models are implemented.

EASY-TO-USE GRAPHICAL USER INTERFACE

To evaluate a skylight using SkyVision, the user simply inputs information in a number of fields.

Inputs include:

Site Location
The user specifies the site latitude, longitude, and time zone (or, choose from a database of major Canadian and US cities), and the ground/surroundings reflectance values.
Sky Conditions
Two types of sky conditions can be selected: Standard skies that are site-independent, or dynamic (real) skies that change with daytime (for example, clear in the morning, partly-cloudy in the afternoon and cloudy in late afternoon). Standard skies include: (1) uniform overcast sky that corresponds to dark thick clouds; (2) CIE (Commission Internationale d'Éclairage) overcast sky that corresponds to thin clouds; (3) CIE average intermediate sky; (4) IESNA (Illuminating Engineering Society of North America) partly cloudy sky; (5) CIE clear sky for industrial areas (with high air pollution); and (6) CIE clear sky for rural areas (with low air pollution). Dynamic skies use a climate data to determine the sky condition.
Skylight Shape and Glazing
Users may specify various skylight shapes found today in the market. Skylight shapes are classified into five categories: dome-like, cone-like, vault-like, light pipe and flat. Under each category, one can simulate a number of shapes. For example, for dome-like skylights, one can simulate circular domes, segmented domes, bubbles, or any other similar shape. Skylight glazing may be multi-pane transparent or translucent. An attached glass database allows users to build skylight products from certified manufacturer glass products. Users may also add their own glass products to the database.
Indoor Space Geometry and Surface Characteristics
The indoor space is composed of the curb (space between the skylight and roof), well (space between the roof and ceiling) and room (space below the ceiling). The user specifies the dimensions of the curb, well, and room spaces, the indoor surface reflectance values, the building orientation, and the skylight position layouts.
Lighting and Shading Controls
Users specify the lighting control strategy (on/off auto, or continuous dimming), the type and position of the shading devices (fixed or movable), and the shading control strategy (time clock, on/off auto, or adaptive).

Comprehensive Outputs

In return for these inputs, SkyVision calculates:

The skylight overall optical characteristics (transmittance, absorptance, reflectance and Solar Heat Gain Coefficient) as a function of the incidence angle and daytime hour. The hemispherical values of the skylight optical characteristics are also calculated under a given sky luminance distribution pattern.
The daylight factor at room floor, ceiling and wall surfaces under a given sky condition.
Total illuminance from sun beam and sky diffuse light at room floor, ceiling and wall surfaces.
The well efficiency and coefficient of utilization.
Percent of the floor surface area covered by the skylights.
Percent of annual lighting energy savings