Influence of Windows on Daylight Entrance and Energy Demand of Housing based on the Dutch Building Code

Abstract

This research investigates the effect of window position and size on building facades on daylight entry, energy consumption, and thermal comfort of buildings. The aim is to find a feasible way to make housing more sustainable and energy efficient in compliance with the Dutch Building Regulations while providing good daylit spaces. This knowledge can be helpful to architects and engineers at an early stage in the design process who intend to design a sustainable building. This research is done in relation to the graduation from the TU Delft Building Engineering Master's degree in cooperation with the company Sweco Nederland B.V. located in De Bilt.
This study developed a parametric model based on the NTA 8800 calculation method for energy demand and the NEN-EN 17037 daylight norm. Two different types of reference building are investigated, a middle apartment in an apartment building and a middle terraced house. The parameters used for this study are the orientation of the building, the height and width of the window (and therefore WWR), as well as vertical and horizontal positioning of the windows, and a balcony cantilever in front of the apartment windows. The results show that:
The lower WWR boundaries are independent of orientation, and therefore, the minimum WWR values per orientation are the same. The lower boundary of the apartment (33%) is strongly influenced by the present overhangs, while the terraced housing requires a minimum WWR of 12%. The results show that the maximum WWR for terraced housing is mostly restricted by the BENG1 requirement (25% -38%), except for the south orientation (36%) which is limited by TOjuli. The maximum WWR of the apartment is restricted mainly by TOjuli (33% - 60%). The BENG1 results show that a north-south orientation for terraced housing is best to minimise energy demand (WWRs of around 38% are possible until requirements are exceeded). For the geometries studied, this research suggests a WWR for an apartment building roughly between 30% and 45% and for terraced housing roughly between 13% and 25% as a starting point. On top of that, it is recommended to install windows in the middle of a facade in terms of horizontal position and in the upper part of the facade in terms of vertical position to maximise daylight entry. Glass below the reference surface height of 0.85m should be avoided.
The results of this research indicate certain guidelines, rules, and statements that can be used when working with the new regulations, of which the most fundamental statement: As a consequence of the updated daylight standard from NEN 2057 to NEN-EN 17037, an increase in WWR no longer directly leads to a higher daylight factor, as it did under the current regulation.
Furthermore, this study reveals clearly that despite the fact that energy demand and daylight are theoretically closely related, regulations are separated more. Daylight and energy demand are better separable (and individually optimised) in regulations than expected beforehand.
The methodology used demonstrates its robustness and practicality in analysing complex problems and obtaining validated results. Therefore, the methodology used can be recommended for further research and larger design projects in practice.