Lighting and energy efficiency: daylighting design for energy saving and visual comfort

The importance of daylight for both energy performance of the building and quality of the spaces implies the need of a more accurate design approach able to take into account the dynamic behavior of daylight.

Recently a number of new metrics was proposed, based on processing illuminance data which are calculated for a user-defined time interval, general corresponding to a year (“climate-based daylight metrics”). The new metrics were defined to assess different aspects concerned with daylight availability within buildings. They are still going through an identification and proposition stage: the CIE, through the research activity carried out by the Technical Committee TC 3-47, is going to assess and validate their consistency, reliability and applicability.

Furthermore a number of numerical simulation tools was developed and made available, which allowed passing from a static to a dynamic daylight building modelling.

The research program is meant to contribute to:

• evaluating the applicability of new indicators which have been proposed to-date to assess luminous environment quantity and quality;
• analyzing the effectiveness of the new metrics in evaluating the impact of daylighting in reducing building energy consumptions;
• guiding the development of dynamic daylight metrics with a summary metric, able to identify conditions when daylight is either lacking or overabundant;
• determining target values for dynamic daylight metrics that satisfy both visual and energy criteria.