ParaSol logo.

A design tool to study the potential of solar protection for different types of sunshades and glazing systems and their influence on the building energy performance at an early design stage.

ParaSol is based on dynamic energy simulations and provides monthly results for the total and direct solar energy transmittance (g- and T- values) of the sunshade and the combination of sunshade and window system and calculates their influence on the building energy performance. The program has post-processors for studies of daylight and thermal comfort.

The user can select between external, interpane and internal sunshades. Within each such group, a number of different geometries and material properties can be selected.

A simple geometric model, which can symbolize a rectangular office module, is predefined. All dimensions can be changed.

ParaSol is mainly intended for simulations of buildings like offices, schools and hospitals, but rooms in residential buildings can also be simulated. Screen Shots


solar protection, solar shading, windows, buildings, solar energy transmittance, solar heat gain coefficient, energy demand, heating, cooling, comfort, daylight



Expertise Required

Basic knowledge about solar radiation, solar shading, windows, energy performance indicators.




architects, building services consultants and other engineers


Input data is separated into three parts: Room, Window and Sunshade. The room data includes specification of the site, geometry, and wall constructions. The window data includes window specifications (i.e. specification of the glazing system).

In the sunshade data part, the type of sunshade is selected. Depending on the type of sunshade, more or less input is required. For example awnings need a precise geometric description while fabric screens are assumed to cover the whole window. The fabric colour or type must also be specified. The program includes a database of some common fabric types on the Swedish market.

Some additional input data can be given for the calculation of the building energy performance: Control of sunshades, set-points for the indoor temperatures (heating and cooling), internal loads, inlet air temperatures and flows, and the efficiency of the heat recovery system.


Tables or diagrams for monthly average solar transmittance (g- and T values), indoor temperatures, energy demands, maximum heating and cooling load, solar insolation, operative temperatures, design days, and energy demands for pre-heating and pre-cooling the room module. Simulated data can be saved to an external file for further analysis in eg. a spreadsheet program.

Diagrams with iso-contours for daylight levels and operative temperatures (or thermal comfort indices PMV or PPD) can be drawn when a simulation of the building energy performance has finished.

Computer Platform

Windows 9x/NT/2000/XP, minimum 64 MB memory, 50 MB of free hard-disk space, and CPU greater than 800 Mhz.

Programming Language

Fortran 90, Visual Basic


Simple user interface, detailed dynamic simulations, detailed models for shading calculations of direct and diffuse solar radiation and calculations of solar transmittance of window systems. The air gap between the window and an internal screen is assumed to be open, but a closed air gap can also be simulated.


Only one strategy for controlling sunshades is available.



Lund Institute of Technology


Lund University
Box 118
Lund 221 00


+46 (46) 222 7358


+46 (46) 222 4719




Free and available for download from