Improving Daylighting Utilization in LTH Study Center

Abstract

Daylighting is a free source of light that fosters a direct connection to nature. It has a great potential to enhance the health and productivity of the building inhabitants, to improve thermal and visual comfort in indoor spaces, and to increase energy efficiency in buildings. LTH study center (Lund, Sweden) is a compact building that was originally designed as a library. The building is nowadays used as a study hub. Due to its compact building form, unsatisfactory daylight conditions occur. This study focused on improving daylighting utilization in LTH study center. Continuous and proportionally larger wall and roof apertures can provide enough uniform light for such building. However, as larger glazing area were needed to improve daylighting, the building’s energy use assessment was also conducted to check if the increase in energy use is within an acceptable range. The improvement focused on side-lighting strategy, providing continuous side windows and more clerestories to allow daylight penetration deeper towards the building core. For the top-lighting system, the current position and size were kept, which resulted in negligible changes in daylighting level. Increased side-lighting measures yielded an overall increase in daylight level of the building. On the other hand, energy demand increased as expected, yet the increase was not significant. After adding more insulation to the building envelope, the reduction of energy use was marginal. Therefore, LCC analysis needs to be conducted to validate the necessity of adding more insulation layer. Moreover, by providing larger glazing area on the facade, the daylight level improved only in the peripheral zones but not in the core zones. To improve the daylight level in the core zones, further study of top-lighting solution is needed. In addition, with continuous side windows, the quality of the view out improved dramatically while the electric lighting dependency was significantly reduced.

Popular Abstract

Improving daylighting utilization in a compact educational building in Sweden.
This study is focused on altering side-lighting and top-lighting strategy to enhance daylight level and to improve view out quality. The impact on energy demand due to the alteration is another concern of the study.
The research was conducted in LTH study center located in Lund, Sweden, a building with a very compact building shape which was initially designed as a library and was renovated into a study hub a few years later. Combination of side-lighting and top-lighting strategies were implemented for this analysis. For the side-lighting strategy, various choices of side window positions, shapes, and size; also additional clerestory were explored. As for the top-lighting, three different shapes and slopes were tested keeping the current position and size. With these variations, the window-to-wall ratio (WWR) and skylight-to-floor ratio (SFR) of the building increased, which would increase the building’s energy demand as well. To check the significance of the increasing energy demand, energy simulations were also performed. As a comparison for the daylight study, certification systems such as Miljöbyggnad, BREEAM-SE, and Swedish Standard SS-EN 17037 were considered. Additionally, a brief calculation regarding the electric lighting dependency was carried out. The results showed, as expected, an increase in both the daylight level and building’s energy demand as the WWR was increased whereas the electric light dependency was reduced. For daylighting results by side-lighting strategy, position showed a significant effect along with increased size of the openings. Higher position and continuous glazing provided better daylight penetration. In existing position and size, the top-lighting was found to produce a negligible effect on the daylight level in functional zones. Although side-lighting succeeded to increase the daylight level inside the building, the improvement was concentrated only in the peripheral areas not in the core areas which lead to a non-uniform daylight condition. Yet, by providing continuous side windows, the view out improved remarkably. However, the energy demand increase was not significant although the WWR increased considerably, window-to-envelope ratio (WER) was found to be more suitable as significant indicator for this study. Adding more insulation layer in building envelope to suppress the increase on the building’s energy demand caused by increased WWR, it was found that the energy demand diminished with one more insulation layer on both the external walls and roof, but the reduction was small. Lastly, energy demand for electric lighting was reduced in the improved combinations from the existing building.
The current daylight level in the building is unsatisfactory where electrical lighting needs to be turned on all the time and the provided view out is very poor. Therefore, it is necessary to improve daylighting inside the building but due to its compact form the task is difficult. However, the study helps to identify the influencing parameters for such a compact building regarding both daylighting and energy demand as well as to understand the way of performing and the extent of impact of these parameters.

• author: Tumpa, Rifat Tabassoom and Eugenia, Inez
• supervisor: Marie-Claude Dubois
• organization: Division of Energy and Building Design; Department of Architecture and Built Environment
• alternative title: Optimizing Daylighting in a Compact Educational Building
• course: AEBM01 20191
• year: 2019
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Daylighting, energy demand, window to wall ratio, daylight factor, daylight autonomy, heating and cooling demand, electric lighting dependency
• language: English
• additional info: Both authors contributed equally to the article.
• id: 8988789
• date added to LUP: 2019-07-02 14:57:07
• date last changed: 2019-07-02 14:57:07