Your focus should be to design the fenestration and overall program in the most efficient way according to the local climate conditions. Put simply; small spaces with high internal loads should be orientated towards the North to avoid solar gains to save energy for cooling, whereas deeper spaces with higher air exchanges rates should be orientated towards the South to maximize utilization of daylight.
For The University of Cincinnati College of Business, we carried out parametric studies evaluating patterns and rhythms of various components, balancing window-to-wall ratios with internal cooling loads in order to meet specific low energy targets. Working strategically with the façade, fenestration and the systems of the building concept, we have managed to lower the energy cost savings by 24 percent compared to similar buildings.
The size and placement of windows is the next step. In commercial buildings, it is crucial to pay attention to the passive energy assumption, as the energy balance here is very sensitive – sunlight and the passive energy that follows can easily affect the indoor temperature by several degrees. For The University of Cincinnati College of Business, we worked with sizing the windows based on orientation. Bigger windows towards the North where we can utilize the diffused daylight and avoid problems with overheating, and more balanced sizing of windows towards the South and West where there is a risk of overheating.
Work comprehensively with measuring and analyzing local and current weather conditions in order to find the ideal balance between daylight and your high performing building. At Henning Larsen, we use dynamic tools such as Diva for Rhino and predictable weather data combined with simulations of the estimated energy demand through Energy+ in the early stages of our design process. We always use dynamic modeling metrics like Spatial Daylight Autonomy (sDA) and Annual Sun Exposure (ASE). ASE tells us how much of a space receives too much direct sunlight, which can cause visual discomfort (glare) or increase cooling loads, and sDA describes how much of a space receives sufficient daylight. Specifically, it describes the percentage of floor area that receives at least 300 lux for at least 50% of the annual occupied hours. Why are both metrics needed? Daylight Autonomy contains no upper limit on illuminance levels — so spaces with too much direct sunlight could appear to do quite well. ASE provides the balance: the proxy for direct sunlight, and an indicator of potential problems. Our goal is to maximize sDA while keeping ASE in check.
Creating a net zero building requires a strong strategy from the earliest design phase – when designing the program -particularly in the façade design. Truly sustainable design is present from the first sketches and informs every stage of the building's construction.