Daylighting and energy analysis of perimeter spaces with dynamic shading

Hui Shen, Purdue University

Abstract

In this work, a building façade is not treated as a single building component, but as a part of building perimeter zones, which may also include controllable electric lighting, shading attachments, HVAC components and indoor environmental parameters. Consequently, façade design becomes part of perimeter zone design, and the objective is to balance the need for daylighting and view versus the need of controlling of solar gains and maintaining human comfort, while at the same time minimizing energy use for air-conditioning and lighting. First, a flexible dynamic daylighting and thermal simulation model was developed, applicable to perimeter spaces with one or several exterior facades equipped with automated interior roller shades (the most common type of shading used in commercial buildings). The model accepts various fenestration properties as inputs, and provides several daylighting, thermal and electric lighting control options. Outputs of the model include the most advanced daylighting metrics, thermal loads, surface and air temperatures and energy consumption for every calculation step -as well as annual indices. Thermal and lighting results were presented for a variety of different envelope options and climates with recommendations for different orientations. It was found that windows occupying 30–50% of the facade can actually result in lower total energy consumption for most cases with simple shading controls, depending on glazing properties. New, innovative and practical shading control methods were developed for maximizing daylight utilization and minimizing building energy consumption. The new control strategies were simulated using the developed integrated model to investigate their impact on outdoor view, daylighting metrics, thermal loads and energy consumption as well as on excessive illuminance that can cause visual discomfort. For the first time, model-based control of shading devices, demonstrated in a comparative way, allowed selection of orientation-dependent control strategies and use of alternate control criteria. At the same time, the interplay between lighting energy use, solar and internal heat gains was studied considering dynamic façade systems in an integrated manner. Experimental studies were conducted to assess the impact of façade design options and related controls and to validate the developed models. Two identical full-scale office spaces with reconfigurable façade and lighting systems were designed and built for this purpose. The rooms were full instrumented with lighting and thermal sensors and equipped with automated interior roller shades and dimmable lighting systems that can be controlled according to the new developed strategies. Shading devices with different properties and different controls were tested extensively to quantify the impact of façade and lighting controls on interior conditions and energy use. A global uncertainty and sensitivity analysis was performed using the integrated model, to identify the most important factors with respect to building thermal and daylighting performance. The uncertainty analysis is based on the Monte Carlo method with Latin Hypercube Sampling, showing the possible ranges in performance indices. The sensitivity analysis uses a variance-based method in the extended FAST implementation. Application of the analysis to perimeter private office spaces showed the first order and total order effects of each studied parameter. Finally, a state-of-the-art tool with a powerful engine and a simplified interface was developed to assess the overall impact of dynamic façade elements and perimeter zone performance. It is intended to provide guidelines and quick feedback to both building design professionals and non-experts and to promote the use of efficient façade controls in the buildings community. (Abstract shortened by UMI.)

Degree

Ph.D.

Advisors

Tzempelikos, Purdue University.

Subject Area

Civil engineering|Mechanical engineering

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