@article {31851, title = {Split-pane electrochromic window control based on an embedded photometric device with real-time daylighting computing}, journal = {Building and Environment}, volume = {161}, year = {2019}, month = {08/2019}, pages = {106229}, abstract = {

Well-designed electrochromic (EC) glazing control can improve the energy performance of buildings and visual comfort of occupants in highly glazed buildings. This paper designed and demonstrated a compact integrated EC glazing automation system to control tint states of a split-pane EC window according to variations of sky conditions. The control is based on monitoring the luminance distribution of the sky and real-time lighting computation for a building interior, using an embedded photometric device (EPD). It optimizes tint states of EC glazing to offer sufficient daylight provision and temper discomfort glare for occupants, which potentially mitigates excessive solar heat gain. {\textquoteright}In-situ{\textquoteright} experiments were conducted in a full-scale testbed to demonstrate the daylighting performance under various sky conditions. Experimental results showed 83\% of the working time for work-plane illuminance (WPI) and 95\% of the time for daylight glare probability (DGP) were constrained in comfort range (WPI[500, 2000] lux, DGP\ <=\ 0.35) by the automated EC glazing (controlled by EPD) under clear skies; 68\% of the time for WPI and 94\% of the time for DGP in confined range under clear skies with thin clouds; 62\% of the time for WPI and 85\% of the time for DGP in confined range under partly cloudy skies.

}, keywords = {daylighting, electrochromic, Embedded Controller, HDR, windows}, issn = {03601323}, doi = {10.1016/j.buildenv.2019.106229}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0360132319304391}, author = {Yujie Wu and Taoning Wang and Eleanor S. Lee and J{\'e}r{\^o}me H. K{\"a}mpf and Jean-Louis Scartezzini} } @article {31495, title = {Efficient modeling of optically-complex, non-coplanar exterior shading: Validation of matrix algebraic methods}, journal = {Energy and Buildings}, volume = {174}, year = {2018}, month = {09/2018}, pages = {464 - 483}, abstract = {

It has long been established that shading windows with overhangs, fins, and other types of non-coplanar systems (NCS) is one of the most effective ways of controlling solar heat gains in buildings because they intercept solar radiation prior to entry into the building. Designers however often specify non-opaque materials (e.g., louvers, fritted glass, expanded metal mesh) for these systems in order to admit daylight, reduce lighting energy use, and improve indoor environmental quality. Most simulation tools rely on geometric calculations and radiosity methods to model the solar heat gain impacts of NCS and cannot model optically-complex materials or geometries. For daylighting analysis, optically-complex NCS can be modeled using matrix algebraic methods, although time-efficient parametric analysis has not yet been implemented. Determining the best design and/or material for static or operable NCS that minimize cooling, heating, and lighting energy use and peak demand requires an iterative process. This study describes and validates a matrix algebraic method that enables parametric energy analysis of NCS. Such capabilities would be useful not only for design but also for development of prescriptive energy-efficiency standards, rating and labeling systems for commercial products, development of design guidelines, and development of more optimal NCS technologies.

A facade or "F" matrix, which maps the transfer of flux from the NCS to the surface of the window, is introduced and its use is explained. A field study was conducted in a full-scale outdoor testbed to measure the daylight performance of an operable drop-arm awning. Simulated data were compared to measured data in order to validate the models. Results demonstrated model accuracy: simulated workplane illuminance was within 11-13\%, surface luminance was within 16-18\%, and the daylight glare probability was within 6-9\% of measured results. Methods used to achieve accurate results are discussed. Results of the validation of daylighting performance are applicable to solar heat gain performance. Since exterior shading can also significantly reduce peak demand, these models enable stakeholders to more accurately assess HVAC and lighting impacts in support of grid management and resiliency goals.

}, keywords = {bidirectional scattering distribution function (BSDF), daylighting, exterior shading, solar heat gains, validation; building energy simulation tools, windows.}, issn = {03787788}, doi = {10.1016/j.enbuild.2018.06.022}, url = {https://www.sciencedirect.com/science/article/pii/S0378778818302457?via\%3Dihub}, author = {Taoning Wang and Gregory Ward and Eleanor S. Lee} } @techreport {29657, title = {Demonstration of Energy Efficient Retrofits for Lighting and Daylighting in New York City Office Buildings}, year = {2017}, month = {04/2017}, abstract = {

The U.S. Department of Energy{\textquoteright}s (DOE) Commercial Buildings Integration (CBI) program{\textquoteright}s mission (and that of the New York State Energy Research \& Development Authority (NYSERDA)) is to accelerate the adoption of cost-effective, underutilized building technologies with large energy savings potential. The key question which CBI asks for each high impact technology is: "What can the DOE do to improve the market adoption of this technology?" Answering this relies on an assessment of the most significant barriers, including:

Innovative, automated shading and LED lighting controls were identified as key technologies that have the potential to significantly reduce perimeter zone energy use and peak demand in existing commercial buildings.\  Technological advances in the field of low-cost embedded controls have enabled high-resolution sensing and more optimal control on a per fixture or shade basis. The Lawrence Berkeley National Laboratory (LBNL) partnered with the Building Energy Exchange (BEEx) and a commercial building owner to evaluate leading-edge technologies on a 40,000 ft2 floor in an occupied, high-rise commercial office building in New York, New York. This {\textquotedblleft}Living Laboratory{\textquotedblright} was monitored for a year prior to and six months following the installation of four sets of lighting and shading technologies and their performance was compared to a parallel reference floor in the same building.

The Living Laboratory demonstrated that there were many competitive products on the market, that the products were able to meet current needs, and that the various advanced features provided significant added value over and above that of conventional products. Monitored data provided detailed insights into how and why each technology performed the way it did, and what the impacts were on energy-efficiency, peak demand, visual and thermal comfort, indoor environmental quality, and occupant acceptance and satisfaction within the resultant environment.

}, author = {Eleanor S. Lee and Luis L. Fernandes and Taoning Wang and Stephen E. Selkowitz and Steven Mesh and Yetsuh Frank and Richard Yancey} }