Designing spaces that are able to balance illumination, glare and solar gains over a whole year is a real challenge, yet a problem faced every day by building envelope designers. To assist them in this search, a full year, climate-based daylighting simulation method was developed, called Lightsolve, meant to be used early on in the design process when façade and space details have not yet been defined. It focuses on the variation of daylight performance over the day and the year, combining temporal performance visualization with spatial renderings, and including an expert system to support a guided search process. This paper describes the foundations and set of innovative simulation resources that Lightsolve offers as a whole, and puts its different components - including a time reduction method, a set of three goal-based metrics and an expert system - back to Lightsolve’s overall context aiming to an early stage, comprehensive, prospective support for daylighting design.