ENERGETIC EFFECTS OF FAÇADE SURFACE GEOMETRY

Abstract

Designing an energy-efficient building with the use of passive design measures is not always possible due to the location, surrounding buildings or site layout. This can result in larger façade areas facing East or West and causes issues with the low sun altitude. The sun can thereby not be blocked constantly, since daylight is needed for the well-being of students and improves their study performance. It was expected to improve the energy efficiency, indoor thermal- and visual comfort by applying a vertical folded façade geometry of the envelope surface. Additionally, a vertical type of façade geometry was rarely touched by literature. Therefore, this study of the effect of a vertical folded facade was carried out in order to find an improved façade design. Thereby included a sensitivity analysis taking into account the heating- and cooling demand, electric lighting, daylight factor and overheating period as indicators. The analysis was conducted on a hypothetical classroom, based on references and located in Amsterdam, with one exterior wall facing East or West. The results showed that a folded façade slightly increases the energy efficiency and mainly the cooling demand of the classroom while the change in window type has a greater impact on the energy efficiency. Also enlarging the distance related to base line (flat façade) lowers the energy efficiency. Furthermore, the daylight conditions mainly decreased and the overheating period always exceeded the maximum allowed time, although a slight decrease was observed by applying a folding façade geometry. The holistic approach used in this work did not generate one specific design.

Popular Abstract

Energetic effect of façade surface geometry

By applying a folded façade for classrooms facing East and West directions, minor improvements were observed on energy efficiency, indoor climate and daylight conditions.

Designing an energy-efficient building and using solar energy in a proper way can sometimes be a challenging task for architects. They have to deal with requested needs, plot layout and surrounding buildings etc. This sometimes results in designs where large façade sections are focused on East and or West. For south facades, solar heat and daylight conditions are mainly easy to solve with overhangs or other shading devices. However, on East and West facades this becomes a hard task, due to lower solar angles close to sunrise and sunset. The sun is then at a low point in the sky and shines straight into the building, causing glare. The solar radiation cannot be kept out instantly with shading devices since the whole window then would need to be covered due to the low sun angle, making the room almost dark. A space with insufficient daylight is absolutely not welcome for school buildings, because kids need daylight for their healthiness and to deliver excellent performances.

In the quest to improve energy efficiency, indoor climate and visual aspects on East and West facing facades the idea came up to use vertical foldings wherein the facade is subdivided, and the gable folding can be moved creating a kind of saw-tooth design. When the sun rotates around the building some direct light will be prevented due to the angle of the fold within the façade. The intention was to lower the required heating and cooling demand plus lowering the energy needed for artificial lighting. Furthermore, the daylight had to be maintained or improved and also the indoor climate required some improvements.

The research and analysis was performed on a hypothetical classroom located in Amsterdam, Netherlands, thus based on Dutch regulations. The study used the following conventional indicators; annual heating- and cooling demand, electric lighting, daylight factor and overheating period. Beside the façade fold, also changes have been made in the window size and window properties to possibly achieve an even better result.

By applying a folded façade, a slightly positive effect on the energy efficiency was found by mainly lowering the cooling demand drastically. The heating on the other hand went up considerably. Unfortunately, the energy use for artificial light stayed the same, because the daylight conditions did not improve. The overheating period, and thus the indoor climate, did not become better by the use of multiple folds.

By applying other windows, with better insulation and different effects on the amount of solar heat and daylight passing through the window, the energy-efficiency improved. Not only on the cooling demand, like at the folding, but fortunately also on the heating demand. Thereby, the heating demand came back at the same demand as the reference case. Unfortunately enough, the new windows had a negative effect on the daylight conditions, thereby increasing the artificial lighting energy.

Overall it can be noted that by applying a vertical façade fold, it slightly improves the energy-efficiency and overheating period with a minimum, but still do not achieve the overheating target. The daylight conditions are easier to fulfill and reduce partially the glare. But despite the enhancement, is it worth the investment?

• author: Kraakman, Lars
• supervisor: Susanne Gosztonyi; Jouri Kanters
• organization: Division of Energy and Building Design
• alternative title: Energy and indoor quality evaluation of West and East facing façade geometries in Dutch school buildings.
• course: AEBM01 20161
• year: 2016
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Energy-efficienty, Thermal comfort, Daylight conditions, Facade surface geometry, Folded facade, East and West
• language: English
• id: 8885667
• date added to LUP: 2016-07-04 11:17:57
• date last changed: 2016-07-04 11:17:57