Schematic Solar Assessment

Regional Sports & Learning Academy Schematic Design -Solar Assessment

Client and project name has been withheld for privacy

Daylighting + Energy Performance Laboratory

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C e n t e r f o r A r c h i t e c t u r a l Te c h n o l o g y University of North Carolina Charlotte School of Architecture

2008 08.02.

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Index Part 1 Massing-Solar Analysis

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Part 1.1 Massing -Solar AnalyEquinox

Part 1.2 Massing -Solar Analysis Feb 21st

Dale Brentrup

Lab Assistants

Rhonda Lowe

Professor of Architecture

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Part 2 Atrium Design-Solar Analysis

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Part 2.1 Roof Design Atrium Axix

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Angled

Convex

Comparative Assessment

Part 2.2 Roof Design Atrium Axix Lab Director

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Part 2.2 Roof Design Atrium Axix

Appendix A Appendix B

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Figure 2a. Southwestern axonometric view of south facing facade of north building and its relationship to the main entry.

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Glossary Artificial Sky

An enclosure that simulates the luminance distribution of a real sky for the purpose of testing physical daylighting models

Daylight Factor DLF

The ratio of daylight illuminance at a given point on a given plane due to the light received directly or indirectly from a sky of assumed or unknown luminance distribution, to the illumination on a horizontal exterior reference plane due to an unobstructed hemisphere of the sky, expressed as a percentage. The daylight factor is the sum of the sky component, the external reflected component, and the internal reflected component.

Foot candle

The unit of illuminance measurement in English units. One foot candle equals one lumen per square foot. One foot candle of illuminance is received by a horizontal surface under and unobstructed sky having a uniform luminance of one footlambert.

Glare

The sensation produced by luminance within the visual field that is sufficiently greater than the ambient luminance to which the eye is adapted, visually causing annoyance, discomfort, or loss in visual performance and visibility.

Illuminance Light Shelf Overcast Sky Photometer

The density of the luminous flux incident on a surface, expressed in units or foot candles (or lux).

A horizontal shelf positioned (usually above eye level) to reflect daylight onto the ceiling and to shield either direct sunlight penetration or glare from the eye.

(C.I.E. Standard Condition) A sky luminance distribution three times brighter near the zenith that at the horizon.

An instrument for measuring photometric quantities such as luminance, luminous intensity, luminous flux and illuminance.

Luminance

or Photometric Brightness (apparent brightness of a surface). Luminous intensity of a surface. The luminous intensity in the given direction of an infinitesimal element of a surface perpendicular to the given direction.

H.D.R. Photography

A set of techniques that allows a greater dynamic range of exposures (the range of values between light and dark areas) than normal digital imaging techniques. The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to shadows.

Radiance

Radiometric measures that describe the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle in a specified direction. They are used to characterize both emission from diffuse sources and reflection from diffuse surfaces.

Visual Light Transmittance (VLT)

The value of visual light transmittance through and specific to a glazing assembly

Appendix A: Glossary of Daylighting Terms

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Mecklenburg County RRSLA

Table of Contents: Revised Ceiling Configuration The effect of the fewer trusses and re-adjusted VLT. Original truss condition.

South Office Daylight analysis Analysis of Direct Solar Penetration and Radiance imaging.

Golf Pro Shop Solar penetration studies

Mecklenburg County RRSLA

Dale Brentrup Andrew Nagle Omar Villa Deana Moore Drew Skau Appendix B: North Laboratory Thermal Environment

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Mecklenburg County RRSLA

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Mecklenburg County RRSLA The physical model has allowed the daylighting study of the exhibition space in the real sky conditions. The artificial sky has allowed for the simulation of light distribution and sectional analysis. This information is also be used to reinforce previous digital analysis.

Appendix C: South Laboratory Thermal Environment

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Mecklenburg County RRSLA The physical model was built based on the adapted baffle design from the previous analysis documents.

The distribution across the exhibition space is fairly uniform through the center of the space and keeps above the metric of 2% daylight factor. There are issues of glare at the window, but with low VLT glass (.47) it lowers glare and allows the depth of light penetration needed in the space.

When compared with previous daylight factor measurements these three graphs show a constant and relatively even distribution across the space.

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Mecklenburg County RRSLA Revised Ceiling Configuration The revised ceiling allows for the effect half the trusses would have in the exhibition space along with the accuracy of the artificial sky.

Appendix D: General Charlotte Climate Data

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Floor Chart showing where sensors were located

Mecklenburg County RRSLA Revised Ceiling Remaking of the roof plane has yielded the expected improvement in light levels in the space. In addition to the improved numbers, the readings have been re-adjusted with the .47 VLT glass in the view-window producing an adjusted average VLT at .59. There is a significant 20%-30% increase in performance over the previous model and the adjusted VLT.

Average DLF chart showing readings in the space

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Floor Chart showing where sensors were located and Daylight Factor across the entire space

Mecklenburg County RRSLA Revised Ceiling/Truss Analysis Sectional analysis through the center of the fitness area shows relatively even distribution, although there are raised daylight factors at the window wall. The lower roof serves both as a light shelf for the exhibition space and also collects light from the view window in the fitness area. All values are weighted with an average VLT of .59, averaging the area’s of .7 and .45 VLT

DLF chart showing readings in the space

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Floor Chart showing where sensors were located and Daylight Factor across the entire space

Mecklenburg County RRSLA Revised Ceiling/Truss Analysis At the fitness area wall light spreads past the wall from the adjacent window wall raising levels behind the fitness areas roof.

It is important to notice that not only are the daylight factors relatively flat they are parallel to the previous daylight factor readings in the center. The fitness area wall also serves to diffuse light coming through the exhibition spaces window wall.

DLF chart showing readings in the space

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Floor Chart showing where sensors were located and Daylight Factor across the entire space

Mecklenburg County RRSLA Revised Ceiling/Truss Analysis Measurements at the window wall reveal that glare is a potential problem in the exhibition space. With the size of the window; the digital model and the physical models support the recommendation to keep the view window glazing at a lower (.47) VLT. This is allowable due to the depth of light penetration it allows.

DLF chart showing readings in the space

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Mecklenburg County RRSLA Digital vs. Physical Modeling

3000 2500

Analysis of both the Radiance images and the physical model show a similarity in both sets of data. Of course both sets of analysis would predict higher levels at the window wall, but the patterns through the space share similar characteristics.

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1000 500 0 1

The graphs of both, Digital and Physical models, have a corresponding nature. Each arrow points out each relative magnitude of illuminance reinforcing the results of our Radiance analysis.

At least 60-65% of the exhibition space has levels that show little or no variation despite the intensity at the view window. This is allowable as the distribution through the space meets the metric of 2% daylight factor

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Digital Model

Physical Model

Comparison of the Physical and the Digital models reinforce similar results above the 2% daylight factor mark needed.

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Mecklenburg County RRSLA

Baffle Detail

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Mecklenburg County RRSLA Previous Roof Analysis Sectional analysis through the center of the fitness area shows relatively even distribution, although there are raised daylight factors at the window wall. The lower roof serves both as a light shelf for the exhibition space and also collects light from the view window in the fitness area. All values are weighted with an average VLT of .59, averaging the area’s of .7 and .45 VLT

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Mecklenburg County RRSLA Previous Roof Analysis At the fitness area wall light spreads past the wall from the adjacent window wall raising levels behind the fitness areas roof.

It is important to notice that not only are the daylight factors relatively flat they are parallel to the previous daylight factor readings in the center. The fitness area wall also serves to diffuse light coming through the exhibition spaces window wall.

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Mecklenburg County RRSLA Previous Roof Analysis Measurements at the window wall reveal that glare is a potential problem in the exhibition space. With the size of the window; the digital model and the physical models support the recommendation to keep the view window glazing at a lower (.34) VLT. This is allowable due to the depth of light penetration it allows.

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Mecklenburg County RRSLA South Offices & Golf Pro Shop Assessment

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Mecklenburg County RRSLA Office Area’s

The Southern Offices suffer from a large south facing window wall that will provide large amounts of luminance into the office.

The design of the building works excellently to manage both summer and winter conditions. With large overhangs and a reasonably sized light shelf, the office spaces are protected from the summer sun and light is allowed to penetrate into the space in the winter. Area’s of concern are the offices on the east end that are receiving large amounts of morning light, thus creating glare and large amounts of solar heat gain.

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Mecklenburg County RRSLA Solar Penetration

The orientation of the office space is not beneficial to daylighting, yet traditional daylight principles have been applied to the faรงade ensuring that natural light is limited in the summer and allowed to raise interior luminance during the winter.

Key issues are solar penetration and glare. These diagrams show the effectiveness of the proposal and its excellent performance. Being that the window wall faces south there is the possibility of glare as it faces the daily sun path.

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Mecklenburg County RRSLA Office South Window Wall

Summer Shadow Range

The south office window wall poses a large risk for glare. The use of a large over hang and adequately sized light shelves serve good daylighting principles and practices. The current design is very efficient at protecting the space from direct summer daylight penetration and allows low angle winter rays to provide a greater luminance in the space. This design follows principles that could also lessen cooling loads in the summer and lessen the need for heating in the winter months.

The Winter sun does produce high daylight factors. Exterior shading can be used but may cause a view problem and become expensive. Interior shade screens can lower interior luminance and be less expensive.

Winter Shadow Range

Winter Uniform Sky False Color Equinox Shadow Range

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Mecklenburg County RRSLA Corner Office Conditions

Winter Morning Shadow Range

Summer Morning Shadow Range

Winter Radiance HDR

Summer Radiance HDR

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The corner offices, being exposed to both the south and east solar conditions, pose a serious threat for glare. The SE corner office performs well with the lower angles of sunlight during the early hours of the morning. The larger rear office does not perform well with the lower winter sun angles and the intensity of the summer sun reflecting off the adjacent north exterior wall into the office space.

This reflectance becomes a problem in the space all year long. This could be resolved by exterior screening, limiting interior heat load, or using a neutral diffuse color on the adjacent north exterior wall to limit its reflective qualities.

Radiance image

Mecklenburg County RRSLA Interior Office Conditions

Original Design

The interior offices are not sufficiently day lit spaces, the light received from the daylight windows don’t provide enough luminance. The small daylight windows don’t provide enough exterior light.

Proposed Design

These spaces would benefit from transom's that borrow light from the greater office area. This may add to luminance levels to the space without undue privacy issues. The transom will raise daylight levels in the space, but will not be sufficient.

Original design with no significant daylight attributes

Proposed design including a transom that improves interior conditions

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Mecklenburg County RRSLA Golf Professional Shop

Winter Shadow study

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12pm

7pm

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Equinox Shadow Study

Summer Shadow study The Golf Pro Shop is similar to the office space.

Penetration is seen through the entire winter day. The problem persists through the equinox where light penetrates through the beginning of the day. During the Summer months there is no penetration.

Interior shading devices could be a inexpensive solution to limiting glare and lowering direct solar penetration rather than exterior devices that could be expensive and limit exterior views.

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