PRECIS: Assessing the potential for renewable energy in cities

• Research unit: EU RFP
• Project number: 97.0096

Key words (English)

Urban form; solar irradiation; daylight; urban microclimate; renewable energy

Alternative project number (English)

EU project number: JOR3-CT97-0192

Research programs (English)

EU-programme: 4. Frame Research Programme - 5.1 Nonnuclear energies

Short description (English)

See abstract

Partners and International Organizations (English)

University of Cambridge (UK), Politecnico di Torino (I), CFD Norway (N), Centre for renewable energy sources (GR)

Abstract (English)

'Solar cities' is an emerging concept which attempts to demonstrate that passive and active solar techniques are able to contribute significantly to the energy balance of urban areas. Optimised penetration of daylight into buildings is also proved to have an important potential for reducing electricity consumption. For such applications, the related solar radiation exploitation systems could be positioned on building facades as well as on roofs.
To assess the energy contributions that can be expected from these natural resources (the sun and the luminous sky vault), the irradiance (in [Wm-2]) and illuminance (in [lx]) falling on building envelopes (facades + roofs) have first to be quantified. However, high building densities usually encountered in the urban context rather complicate this task. Two issues are of particular importance: the dynamic shadow patterns due to neighbouring buildings and interreflections between building facades.
Our contribution to the PRECis project presents a method, which address these issues by numerical simulations. The resulting tool comprises four distinct components:
· a method to produce accurate anisotropic average sky models from meteorological data;
· a dedicated program to handle simplified geometrical descriptions of the urban areas under investigation;
· a set of automated procedures to perform the numerical simulations using RADIANCE, a ray-tracing program originally developed to model light propagation within buildings;
· a performance analysis scheme based on irradiation and illuminance distributions over the building envelopes.
This method has been applied to several 'virtual' and real urban case study sites. First results were presented at the Passive and Low Energy Architecture (PLEA 2000) Conference at Cambridge (UK) in July 2000.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0096