Daylighting in Architecture PDF

The term "Daylighting" refers to the use of natural light in building design. Through the careful arrangement of windows, skylights, and...

The term "Daylighting" refers to the use of natural light in building design. Through the careful arrangement of windows, skylights, and reflective surfaces. This technique provides numerous benefits, including increased productivity, better connection to the outdoors, improved health, and energy savings. What is daylighting? 2 What is the difference between Daylight and Sunlight? Sunlight: is the light that enters a space directly from the sun. This type of light is generally not suitable for lighting an interior space. Direct sunlight can produce glare and excessive heat gain. Daylight: is the desirable natural light in space (diffuse natural light from the sky). Daylight results in a perceived even distribution of light that avoids direct sunlight’. For Design purposes, Daylight is taken into consideration, whereas the direct sunlight creates light that is too intense that cause unwanted heat.  Daylight Daylight is an essential component of passive building design. It impacts visual and thermal comfort, and understanding how it enters a building and how to use it effectively is key to successful daylighting. Component of daylighting illumination in buildings (Mardaljevic, 2012) 11/27/2023 4 Factors affecting Daylighting in Buildings The quantity and quality of daylight in buildings is continually varying due to the natural changes in sun and sky conditions from one moment to the next. These changes have components that are random (e.g., individual cloud formations), daily (i.e., progression from day to night), and seasonal (e.g., changing day length and prevailing weather patterns). Too bright at a certain time Not bright enough 5 Benefits - Conducting solar study and analysis for buildings Choosing better sustainable strategies to benefit from daylighting Utilizing solar renewable energy sources, i.e., PV panels Choosing passive design strategies such as passive heating/cooling Reducing the overheating inside the building due to heat gains. Solar analysis is crucial for effectively harnessing solar energy, ensuring the optimal performance, efficiency, and sustainability of solar energy systems. 7 What is Solar Analysis? "Solar analysis" generally refers to the evaluation and analysis of solar energy potentials and characteristics at a specific site or area. It involves assessing factors like solar irradiance, sun path, shading, and other environmental and geographical conditions that can affect the performance of solar energy systems, such as solar photovoltaic (PV) panels and solar thermal systems. 8 DESIGN GUIDE FOR EDUCATIONAL BUILDING RETROFITTED FACADES TO ACHIEVE LOW ENERGY PERFORMANCE DAYLIGHT IN ARCHITECTURE Importance 1- Optimization of Solar System Design: Solar analysis helps in designing efficient solar energy systems by determining the optimal orientation, tilt, and type of solar technology suitable for a specific location. 2- Evaluating Solar Potential: it allows for evaluating the potential solar energy of a site for making decisions regarding the utilization of solar energy systems. 3- Enhancing Energy Performance: it allows for better building energy performance through the utilization of solar energy systems and reduction of overheating hence lower cooling loads. 4- Environmental Considerations: It contributes to environmental sustainability by promoting the effective use of renewable solar energy, reducing reliance on fossil fuels, and mitigating greenhouse gas emissions. 5- Psychological Considerations: It contributes to the human wellbeing and psychological health as daylighting plays a significant role 13  Importance Using solar power reduces a building's environmental impact up to 90%. Passive design saves on energy costs by using free sources like the sun's heat and light. Correct design can turn the sun's energy into an asset by allowing it to penetrate building through windows and outer walls. 14 Solar heat gain Solar heat gain Transparent elements Opaque elements Windows/ Curtain walls Wall/ roof  Solar heat gain through transparent elements- windows Solar heat gain = Global irradiance (w/m2) x Window area (m2) x Solar gain factor (decimal fraction) Qs = G × A × ϴ In USA, S H G C (Solar Heat Gain Coefficient) ϴ is used to express solar gain factor OUT IN G l a z i n g type Solar G a i n Absorbed Factor Transmitted Single C l e a r Glass- 0.76 6 mm Re-emitted OUT Re-emitted IN Double C l e a r 0.64 Glass- 6 mm & 6 mm Single reflected 0.36 Glass- 6 mm Two types of solar analysis could be done using Revit: 1- Solar Study: Visualization of the Sun’s Path and the shadows that a site or building element generates during a specific time. 17 Two types of solar analysis could be done using Revit: 2- Solar Analysis: Visualizes and quantifies the distribution and intensity of solar radiation on surfaces. The analysis considers shading by adjacent objects, such as vegetation and surrounding buildings. It can help identify locations for maximizing solar gain by considering shading effects and seasonal variations in solar radiation. 18 Sun Position Altitude: the height of the sun in the sky on the sun path (vertical angle between the sun and the ground). Azimuth: the position of the sun from the north (horizontal angle of the sun from the north) Solstice: the extremes of the sun’s position (winter and summer solstice). equinoxes: the average sun positions (Autumn and Spring). 20 Solar/Shadow Study-Sun Path Understanding the path of the sun during extreme periods, such as specific times of the day, particular days, or seasons is crucial. Here are some things to consider for different seasons:- Summer: During summer, when the sun is high in the sky, it's important to study its path on the summer solstice day when the sun is at its highest noon altitude. This will help devise ways to minimize overheating and choose passive cooling strategies. - Winter: In winter, the sun is low in the sky. To make the most of the sun for passive heating strategies, it's important to study its path on the winter solstice day when the sun is at its lowest noon altitude. - Spring and Autumn: The equinoxes are the times of average sun positions during spring and autumn. 21 Different times through the day Analyzing the sun's movement and its impact on built environments during various times of the day is vital. This time-specific analysis can be essential for creating comfortable, energy-efficient, and sustainable spaces. Morning Interval: Warm-up Spaces: Morning sunlight can be gentle and, in colder climates, can be used to heat spaces passively. This can reduce energy demand from heating systems during the early hours. Glare Prevention: Low-angle morning sunlight can cause glare. Effective shading or blinds can be employed to minimize this discomfort. 22 Different times through the day Noon: Reducing Cooling Load: the sun can cause significant heat gain, especially during summer months. Analyzing its impact can guide the design of shading devices, facade materials, and insulation to reduce the cooling demand. Passive Heating in Cold Climates: Capturing the sun's heat during noon can help reduce heating loads in cold climates. South-facing windows can facilitate this, but ensuring the space doesn't overheat during warmer periods is important. 23 Different times through the day Occupancy Hours: Daylighting Benefits: Harnessing natural light during the main occupancy hours can reduce the need for artificial lighting, thus saving energy. This decreases electricity consumption and can improve occupants' well-being and productivity. Avoiding Glare: While daylighting is beneficial, it's equally important to prevent glare, which can cause visual discomfort. Solutions can include light shelves, blinds, or diffused glazing. 24 Sun Path To understand the impact of the solar position on your building, you can use Visualization the Sun and Shadows settings in Revit to visualize the sun’s position at your location at any time of the day or of the year. You can also see the shadows that your project will be cast upon the surroundings as well as seeing the shadows cast upon your building surfaces. This feedback about the sun and shadow locations can help you identify surfaces with great solar potential and spot surfaces that could benefit from shading. 25  Daylighting simulation for different times 11/27/2023 26 Factors affecting Daylighting in Buildings For any given sky and sun condition the quantity and character of daylight in a space will depend on: the size, orientation, and nature of the building apertures; the shape and aspect of the building and its surroundings; and the optical (i.e., reflective and transmissive) properties of all the surfaces comprising the building and its surroundings. The locations and size of apertures. Windows and other openings facing the sun receive more direct sunlight than those facing away, but excessive light can cause glare and overheating. 27 Light Distribution & Glare For true visual comfort, you don't just need the right amount of illumination. Light needs to be well distributed to avoid discomfort. Evenly-distributed light is critical to good daylighting, so apertures that are evenly distributed are useful. 11/27/2023 29  Glare Areas of high brightness right next to areas of low brightness cause glare, making people uncomfortable. Glare is especially important to control when using daylighting, since direct sunlight is so bright. 11/27/2023 30 Redirecting Light Redirecting light is the use of building elements to bounce sunlight into more desirable locations in the building. Light shelves and baffles are two strategies that can distribute light more evenly. Light Shelves To evenly distribute light, it is often desirable to bounce sunlight off of surfaces. Direct sunlight on work surfaces often causes glare. Light shelves are devices that both shade view windows from glare and bounce light upward to improve light penetration and distribution. 11/27/2023 31  Light Shelves Light shelves on east and west orientations may not bounce Light shelves and vertical fins do not need to be opaque; when light that much further into the spaces but are an effective they are transparent but diffusive, they can help evenly means of reducing direct heat gain and glare. distribute light without reducing the total amount of light significantly. 32 Illuminance Illuminance – is the quantitative expression for the luminous flux incident on unit area of a surface. A more familiar term would be “lighting level”. It is the measure of light currently used by most performance indicators to determine daylight availability in the interior. Illuminance is expressed in lux (lx), one lux equals one lumen per square metre (lm/m²). In Imperial units the unit is the foot-candle which equals lumen per square foot (lm/ft²). 34 Comfortable Illumination Levels The values above represent the total illumination available from the sky. As a designer, your job is to make sure that the occupants of your building have the right level of light for their activity, and try to get as much of that light as possible from natural light. These levels are usually measured on a working surface in the building. Areas can be too dim or too bright, and these levels depend on the task. The brightness required to make jewelry or assemble electronic components is far greater than the brightness required to safely walk to a room's exit. The following is a table of commonly recommended light levels for different activities. To design for the activities in your program, see local codes or green building certification standards. 35 Dynamic Daylighting metrics Consider daylight over a period of time, such as a year. Use actual occupied hours. Use actual climate conditions (weather files). Examples: Spatial daylight autonomy sDA and annual sunlight exposure (ASE). 11/27/2023 37 Spatial Daylight Autonomy (sDA) sDA is the percentage area of the analyzed space that is above a certain lux level (e.g. 300 lux) for a certain percentage of the time (e.g. 50% of the time) or more during occupied hours (e.g. 8:00 am to 6:00 pm). It is a metric describing annual sufficiency of daylight levels in an interior environment. The duration/effective times chosen need to be aligned to the requirements. For example, sDA300,50% would be the resultant sDA for an analysis with an illuminance threshold of 300 lux on the chosen horizontal surface that is exceeded for more than 50% of the annual occupied hours. 11/27/2023 38 Annual Sunlight Exposure (ASE) describes the annual potential for visual discomfort in a space. ASE is the percentage of an analysis working plane area that exceeds a specified illuminance level more than a specified number of hours. LEED v4 IEQ-Daylight Option 1 limits 10% of the working plane area to 1,000 lux for 250 hours per year. In the example below, 20.8% of the working plane area height exceeds the specified illuminance level of 1000 lux for more than 250 operational hours. 11/27/2023 40