Ball State University Department of Architecture Spring 2017 Grondzik

Transcription

1 ASSIGNMENT THREE Delightful Daylighting DUE: various dates POINTS: 7 of 45 Objectives: The intent of this assignment is to provide hands-on experience with the use of daylighting models as a design and evaluation tool and with the application of daylight factor as a design criterion and performance variable. Equally important, the assignment should provide a sense of how a daylighting system performs and how various components contribute to this performance. ARCH 273: ENVIRONMENTAL SYSTEMS 1 Ball State University Department of Architecture Spring 2017 Grondzik This assignment asks you to design and evaluate a daylighting system for a typical K-12 school classroom, assuming these conditions: new construction LEED certification for the project is desired a reasonably typical site context for the building housing the classroom the classroom is in a single-story building and is abutted by other classrooms, room dimensions as per Figure 1, and the classroom is situated in a double-loaded corridor configuration. A physical daylighting model MUST be prepared and used as a primary means of design evaluation. This assignment must be completed individually. A base (floor) for your model will be available in the mirror sky lab and you will place your model (consisting of four walls and a roof) onto (actually around) this base. Details and dimensions are shown in Figure 1. Expected Design Effort: Design a daylighting system that you believe will provide appropriate daylight for the space and scenario described above. The daylighting system should respond to the following design intents and to the context of the functions and location of the building and space type. The design intents are: (1) daylight illuminance will be appropriate to a LEED green building, (2) views will be available to space users, (3) glare will be minimal. You will need to benchmark each of these intents with reasonable design criteria before embarking on design. You will be using a mirror sky as the primary testing instrument. This device simulates overcast sky conditions. If you wish to design and or test for clear sky conditions ask how to handle such a situation. As this is likely your first attempt at daylighting design, feel free to explore and experiment. For this assignment, process is as important as outcome (although results are not irrelevant). Design decisions that you will need to make include: the basic location of apertures (openings) toplighting with clerestories, sidelighting, or a combination of both approaches are available options (this decision will affect quantity of light, patterns and ease of distribution, the potential for direct and/or reflected glare, and solar heat gain); the size of apertures generally, the greater the aperture size the greater the quantity of daylight admitted (and the greater the potential for glare and solar heat gain); the type of glazing in the apertures single, double; clear, translucent, reflective, absorptive; use of auxiliary devices shading elements (typically used to control glare and reduce solar heat gain), light shelves, etc. (to enhance daylight distribution, control glare, and perhaps control solar heat gain); interior surfaces and finishes which can enhance or impede daylight distribution throughout the space ceiling/roof geometry. Daylighting Evaluation Effort: You will evaluate the daylighting system that you design. This evaluation will involve qualitative ( what do you think ) and quantitative (physically measured) aspects. Qualitative evaluation of daylighting proposals is generally fairly easy when using a daylighting model. Simply view

2 the model interior under appropriate lighting conditions and decide whether the outcome as seen in the model is as intended and acceptable. Issues to consider when making a qualitative evaluation include: the general adequacy of daylight, appropriate distribution of daylight throughout the space, control of glare, views (wanted or unwanted), privacy (if important), security potential, maintenance ease or difficulty, and so forth. Such evaluations can be made by the designer directly from the model and by a client (if so desired) via digital images of the model. Quantitative evaluation is also relatively easy (although requiring some equipment and planning). Quantitative aspects that are usually addressed include: daylight factor values (using comparative illuminance measurements), and solar radiation control performance (using sunpeg charts and observation). More sophisticated glare analyses can be conducted if appropriate equipment (such as a luminance meter or calibrated high-contrast digital imagery) is available. Daylighting Models: Daylight (and light in general) models and scales wonderfully. If a model accurately represents the relative dimensions of a space, the positions of apertures within the envelope, the reflectances of interior surfaces, the transmissivity of glazing materials, and the general character of the surrounding environment then the model (if at a reasonable scale) should provide a very accurate estimate and picture of how the actual space will perform with respect to daylighting. Generally, daylighting models are built for internal looks their external appearance is usually not a concern. Things to consider when constructing a daylight model: scale: any reasonable scale can work; reasonable typically means large enough to work on easily and to see into without contortion; to conserve materials you may wish to start with small-scale study models and build up to a largerscale final model as appropriate to the size and complexity of the space being considered; the size of the model for this particular assignment is defined in Figure 1. materials: cardboard or poster board are commonly used as base construction materials; foamcore board (which is translucent) may be used if it is rendered opaque by application of paint, foil, or dark paper. joints: all joints in the model must be sealed light-tight (otherwise light will enter through openings that will not exist in the actual building). finishes: interior finishes must accurately represent the reflectances of intended finish materials (colored paper, markers, paint, etc. provide fair options in this regard); exterior finishes are primarily of concern when they will reflect daylight into the building (roof or ground surfaces, walls, adjacent buildings, etc.); if a model or photographs of a model are to be shown to a client the actual colors of finishes (not just reflectances) become important. viewport(s): the model should be provided with a viewport so that you can look into the space and see what an occupant would see without blocking an intended aperture or introducing an unintended aperture; a viewport large enough to accept a camera lens is a good idea; a drape of dark cloth can block unwanted light entry through the viewport. there must be no openings in a daylighting model other than those that will be in the constructed project; a daylighting model must be enclosed (it cannot be a movie set front). apertures: installing glazing in a scale model can be difficult, thus apertures are often simply left open which is acceptable as long as the effect of intended glazing is mathematically considered (for example, if glazing with a visible transmission of 80% is to be used, the observed interior illuminance in a model with open (unglazed) apertures should be reduced by a factor of 0.8). The use of different glazing types in the same space (for example, clear windows and translucent skylights) gets much trickier ask about this. Deep sills, extensive mullions, and light shelves should be modeled. Normal wall thickness can typically be ignored in the model. orientation: the model must indicate intended site orientation (which, although not a factor under overcast skies, is critical to evaluation of direct solar radiation control). Assignment Deliverables: A summary report (submitted as a single pdf file) with the following information defines the minimum requirements for fulfillment of this assignment: an introduction to the assignment that describes the specific context for your design a design narrative that explicitly and clearly states your daylighting OPR (design intent and design criteria), and that effectively answers the following questions: why the particular approach to daylighting was selected, why the area of aperture used was considered appropriate, why daylighting system appurtenances (such as shading devices or a light shelf) were included (or excluded), and why the particular interior reflectances were selected;

3 a narrative evaluation of the QUALITATIVE aspects of the daylighting system performance as experienced via the model including a brief discussion of the solar shading potential of the design; a narrative evaluation of the QUANTITATIVE aspects of the daylighting system performance centered around an explicit comparison of pre-measurement estimates of daylight factors at nine key locations in the space versus measured daylight factors at these same locations (using a floor plan of the space showing the nine key locations with comparative DF values clearly indicated see Figure 2); an estimate of the maximum and minimum daylight illuminances (as per class discussion) in the space with a comparison to design guideline recommendations; a statement of lessons learned (design lessons and analysis lessons); at least one interior photograph showing daylighting as experienced in the completed model. Schedule: There are several due dates related to this assignment: draft daylighting models will be reviewed during class on 17 February. A model adequately developed to allow comment on appropriateness must be presented at this time, along with a draft of your design intent/criteria statements and your estimate of daylight factors (see Figure 2). daylight factor measurements using your final model will be made during a lab session on (or about) 24 February. the summary report (see above) must be submitted not later than 1 March. A successful assignment submission will: (a) demonstrate an interest in, and engagement with, the design of daylighting systems; (b) fully address the stated deliverables in the form of a complete report; and (c) demonstrate skill in writing/ reporting. An exemplary assignment will do the above and also show an interest in exploring daylighting design and performance potentials by exceding the minimum expectations. The assignment report will be submitted electronically as a pdf file (Subject: 273-A3-nnn). Use the file name: 273-A3- nnn. daylighting is more than simply installing a few skylights. It is a dynamic lighting technology that involves considerations of heat gain, glare, variations in light availability, and sunlight penetration into a building. Gregg Ander: Daylighting Performance and Design When good lighting design is integrated with good spatial composition, and when psychological impairments to human comfort are eliminated, architecture comes to life in a meaningful and gratifying way. Lou Michel: Light: The Shape of Space

4 Figure 1. Exploded view of daylighting model arrangement, showing base dimensions, situation of classroom within the building context, and opportunities for placement of daylighting apertures.

5 Figure 2. Locations of illuminance sensors relative to the classroom floor plan; sensors are centered on three axes in the East-West direction, but are not evenly spaced North-South. The center of the bottom sensor row is 2.2 from the South wall; the center of the next row of sensors is 4.8 above the center of the bottom row; the center of the top row of sensors is 0.9 below the North wall. When installed, the sensors will be about classroom task height. There is no defined orientation for the actual classroom--north is only used to refer to the top of this floor plan.