Evaluation of lighting conditions in portable classrooms and analysis for alternative daylighting systems

Lighting conditions in multiple classrooms in central Texas were assessed, and the feasibility of improving portable classroom daylighting via alternative daylighting systems was also evaluated. Results indicate that surveyed portable classrooms generally provide sufficient levels of light with artificial lighting systems, but have less uniform lighting distribution than permanent classrooms. To evaluate the daylight availability in portable classrooms, a model was developed and verified using field data. Climate-based daylighting simulation was performed using DIVA for Rhino, which uses Radiance and DAYSIM as simulation engines. Results from the annual daylighting analysis suggest that limited amounts of daylight were available in portable classrooms over the course of a year. In order to assess the feasibility of improving portable classroom daylighting conditions, parametric studies were completed to investigate how different factors affect the levels of light in classrooms. Simulation results suggest that increasing window area and higher window placement allow more light into the classroom. Different external shading systems also affect the indoor daylight level. However, the impact of other factors, including building orientation, ceiling-to-floor height, and classroom length-to-width ratio is minimal. While changing the window systems for an existing portable building can require a large construction effort and financial commitment, retrofitting with tubular skylights is a more approachable option. Daylighting analysis shows eight 356-mm (14-inch) diameter tubular skylights can provide the portable classroom with a sufficient light level for more than 60% of occupied hours. When daylighting alone cannot provide sufficient light, lighting control will successfully combine a daylighting system and an artificial lighting system to provide an adequate lighting environment.Civil, Architectural, and Environmental Engineerin

Qualitative and quantitative optimization of skylights : a comprehensive and inclusive analysis of skylight sizes for an office while providing enough daylight, avoiding glare and saving energy

While windows connect inside to outside, daylight entering through windows is a key element in architectural design. Although electrical lighting is able to replace daylight as an essential lighting requirement, daylight has qualitative and quantitative aspects that distinguish it from its competitor, electrical lighting. One of the most unique characteristics of daylight is its variability in time, including different qualities of daylighting from sunset to sunrise, and from equinox to solstice. In addition, by regulating a circadian rhythm and hormone secretion, daylight impacts the physiological and psychological well-being of human beings. Moreover, daylight through windows carries information that flows from outside to inside and makes occupants aware of the outside world. While availability of daylight has been praised in building design, uneven distribution of daylight, reflective surfaces and excessive daylight may cause glare issues and visual discomfort which need to be avoided in daylight design. Beyond all the qualitative aspects of daylight, daylight, as a free resource, is able to illuminate the space and replace electrical lighting and lower electricity utility bills. This quantitative aspect of daylight has been the center of attention among researchers, designers and builders, as lowering CO₂ emissions and environmental design have gained momentum in the building industry. Different stakeholders have various interests in qualitative and quantitative aspects of daylight, which eventually shape the design context. The interests of different stakeholders, including owners, environmentalists and occupants, may merge or conflict in different projects, which shows that daylight quality and quantity may have different weights, depending on the context of the project at hand. This dissertation aims to provide an algorithmic platform to consider a context for skylight design by including all the interests of different stakeholders while either scaling importance of the different interests or requiring minimum qualities and performance targets. This dissertation proposes different methodological approaches for its platform to include both qualitative and quantitative aspects in designing skylights for a one-storey office building in different climates. Three different approaches are proposed in this dissertation, encompassing unconstrained optimization, constrained optimization and monetary metrics. In the unconstrained optimization approach, the algorithmic platform has been developed to implement Parametric Analysis (PA) and Gradient Descent (GD) methods in order to optimize Skylight to Floor area Ratio (SFR) while saving energy consumption, as a quantitative aspect of daylight, and improving daylighting quality by providing sufficient daylight without causing glare discomfort. This platform was built as an Inclusive Integrative Algorithm (IIA) to weight different qualitative and quantitative aspects of daylight. The algorithm is able to perform single or multi-objective optimization by either applying GD or PA. In this approach, a single-objective optimization, considering only energy efficiency, showed that the optimal SFR was 6% in the examined climates of Austin, Chicago and San Francisco, for 300 lux lighting level and Lighting Power Density of 0.8 watt/sqft. The unconstrained optimization approach implemented a weighting system for an aggregated metric, including Mean Daylight (MD) and imperceptible Daylight Glare Probability (iDGP) and Ratio of Energy Saving (RES), which resulted in a SFR of 11% as the inclusive optimal solution for all the examined climates. In addition to the discussion of inclusive optimization considering both daylight and energy performance and scaling their importance, this dissertation initiated the use of GD for the unconstrained optimization in single and multi-objective optimization. The result showed that GD is considerably faster than the traditional method, PA, while predicting the optimal solution with higher resolution. For example, GD resulted in 6.22% SFR for the San Francisco climate as an energy efficient optimal solution by only 9 iterations. However, PA required 10,000 iterations to find the optimal solution with the same resolution. Thus, GD has shown a promising result for the future of multi-objective optimization in building design. In addition to the unconstrained optimization, this dissertation applied the second approach, constrained optimization, by imposing different thresholds for two sets of metrics, including daylight availability and glare. Where Useful Daylight Illuminance (UDI) and spatial Daylight Autonomy (sDA) of 100% were used, the inclusive optimal SFRs were 9-10%, 8-10% and 9% for the climates of San Francisco, Austin and Chicago, respectively. For the other set of daylight metrics, MD of 50% and Mean Daylight Glare Probability (mDGP) of 35% were used, which resulted in optimal solutions of 7-14%, 7-11% and 8-13% SFR for San Francisco, Austin and Chicago, respectively. Therefore, multi-objective optimization considering both daylight and energy performance resulted in different inclusive optimal solutions to energy optimization alone. The study also concludes that optimal solutions depend on applied metrics and daylight thresholds. For the third approach this research investigated the monetary gains from energy efficiency and increased productivity. Assuming that productivity does not occur in spaces with poor daylight performance, inclusive optimal solutions will be the scenarios that most probably boost productivity. The study indicated that the energy cost saving is always negligible compared to the monetary gains from minimum increased productivity (1%). This conclusion may influence an owner’s perspective toward the quality of daylight performance and its resultant productivity increase. Although the proposed algorithm (IIA) has been used to perform multi-objective optimization for skylight design, this platform can be used in the design process to optimize any fenestration, including widows, based on daylight availability, glare and energy factors. GD as one of the contributions of this dissertation is a faster and more accurate method which can facilitate the application of multi-objective optimization for daylight analysis in the early stage of design.Architectur

Daylight and Architectural Simulation of the Egebjerg School (Denmark): Sustainable Features of a New Type of Skylight

This article discusses the performance of a new skylight for standard classrooms at the Egebjerg School (Denmark), which was built ca. 1970. This building underwent important reforms under a European project to which the authors contributed. This research aimed to create a new skylight prototype that is useful for several schools in the vicinity, since there is a lack of educational facilities. The former skylights consisted of plastic pyramids that presented serious disadvantages in terms of sustainability matters. During the design process, the priority changed to studying the factors that correlate daylighting with energy and other environmental aspects in a holistic and evocative approach. Accordingly, the new skylight features promote the admittance and di usion of solar energy through adroit guidance systems. In order to simulate di erent scenarios, we employed our own simulation tool, Diana X. This research-oriented software works with the e ects of direct solar energy that are mostly avoided in conventional programs. By virtue of Lambert’s reciprocity theorem, our procedure, which was based on innovative equations of radiative transfer, converts the energy received by di usive surfaces into luminous exitance for all types of architectural elements. Upon completion of the skylights, we recorded onsite measurements, which roughly coincided with the simulation data. Thus, conditions throughout the year improved

An evaluation study of miniature dielectric crossed compound parabolic concentrator (dCCPC) panel as skylights in building energy simulation

The potential of miniature dielectric crossed compound parabolic concentrator (dCCPC) panel as skylights for daylighting control has drawn a considerable research attention in the recent years, owing to its feature of variable transmittance according to the sun position, but the viability of using it as skylights in buildings has not been explored yet comprehensively. This paper aims to study the feasibility of utilizing miniature dCCPC panel as skylight in different locations under various climates in terms of energy saving potential besides its daylighting control function. The transmittance of dCCPC panel varies at every moment according to the sky condition and sun position. Due to this specific property, this study novelly implemented a polynomial formula of the dCCPC transmittance in the Grasshopper platform, from which EnergyPlus weather data can be called to calculate the hourly transmittance data of dCCPC skylight panel throughout the whole year. An hourly schedule of transmittance is generated according to the hourly sky condition determined by the daylight simulation through Radiance and Daysim, and is then input to EnergyPlus simulation to predict the energy consumption of a building with dCCPC skylight. Fourteen locations around the world are therefore compared to find the most appropriate place for using miniature dCCPC panel as skylights. The energy saving in cooling, heating and lighting with use of dCCPC skylight panel are investigated and compared with low-E and normal double glazing. The results show that the dCCPC skylight panel can reduce cooling load by mitigating solar heat gain effectively although its performance is affected by several criteria such as sky conditions and local climates. It is generally more suitable for the locations with longer hot seasons, e.g., Log Angeles, Miami, Bangkok and Manila, in which dCCPC could provide up to 13% reduction in annual energy consumption of building. For the locations having temperate and continental climates like Beijing, Rome, Istanbul and Hong Kong, a small annual energy saving from 1% to 5% could be obtained by using dCCPC skylight panel

Simulation of Daylighting Conditions in a Virtual Underground City

From the Piranesi fantastic architectures to the animation movies and video games of the last thirty years, a new design approach has been introduced and developed: the design of the virtual space. Designing the "virtual" means experiencing a multidisciplinary approach where architecture, engineering, and urban planning meet the new horizons of information and communication technology. This study is focused on virtual space, which is an underground city. Mankind have always made and used underground environments: the possibilities of unlimited spaces to potential development, the reduced needs for raw materials for the construction and the protection from outdoor weather are some of the reasons that prompted humans to the realization of underground spaces in the past. These reasons and the availability of innovative technologies could encourage a breakthrough in the realization of new underground environments. A recent example is represented by the Underground City of Montreal (RÉSO). We present the architectural design of a virtual underground city, which is called Arch[ane], and its evaluation. The underground city is modular and the studied module is composed of eight floors with a total depth of 400 m and dimensions of 800 m × 800 m. The study comprises the evaluation of the effect of sunlight on each eight floors of the city. Daylighting simulations were performed considering different cities at different latitudes, days, and hours. The results have shown that the particular design of the underground city with skylights gives significant values of illuminance at a certain depth. Furthermore, the simulation results show how huge can be the potentialities of software to simulate extremely big environments

Lost Shadows

There are thousands of pages of technical argumentation on lighting. We could say that there is already a legacy of technical lighting. It is the result of the activity of technically oriented people. In the 1900, CIE was founded to research oil socks and their properties. Standardization got a huge boost in 1931 when CIE introduced international trichromatic colorimetry system, known as “CIE System”. Engineers became active in illumination engineering societies. Sadly, the more visual skills of the lighting designer started to ebb. The lighting design work shifted from the hands of visually oriented people to the hands of technically oriented people. Engineers have done a good job as far as the quantity and distribution of light, but lighting design is at the same time unbalanced and skewed. Because of this, projects also look technical and often suffer from lack of visual beauty. It is good to look at and study lighting with open eyes, and to not judge earlier activities, solutions, norms or recommendations. It is also good to carefully study existing solutions and their connection to technical lighting recommendations. It opens doors for better architectural lighting design solutions. Recommendations are really only recommendations, not solutions for lighting design projects. They are only one tool, which must be used very carefully. Projects late in this thesis work are good examples to help to understand recommendations and put them in the right perspective as a helping tool. This thesis work is focusing on finding back the tools for beautiful architectural lighting solutions. It is not easy task after decades in darkness and under the influence of strong technical lighting eras. Thesis is divided in 2 parts. Part 1 is the core of my Thesis in nutshell and Part 2 has more detailed information for readers who want to learn more on architectural lighting design

Authenticity of the Light Environment of the Pennsylvania Academy of the Fine Arts

Daylight is one of the essential elements in the human experience of architectural space, and this is especially the case with the historic buildings that predate the wide-spread use of electric light. With a historic building, the architect’s original design intent for daylighting may be diminished by a variety of factors: environmental context, replacement of glazing material, soiling, window treatments, introduction of artificial light, interventions for the improvement of energy efficiency, and removal or abandonment of external shading devices such as shutters. By operating computational simulation of the indoor daylight environment on a chosen historic building, the Pennsylvania Academy of the Fine Arts, this thesis is to estimate how light quality has altered over time and how it has changed the viewer’s appreciation of a space