ARCH 447 Electrical Services - LightingARCH 447 Electrical Services - Lighting

Christoph Reinhart, Ph.D.Christoph Reinhart, Ph.D.

Oct 20: Lighting Simulation I - EcotectOct 20: Lighting Simulation I - Ecotect

Shading analysisEcotect Daylight Factor analysis

1 Sep 1 Vision and Color

2 Sep 8 History of Lighting

3 Sep 15 Electricity

4 Sep 22 Lamps

5 Sep 29 Field Trip – custom fixture manufacturing workshop tour

6 Oct 6 Building Simulation & Daylighting Principles

7 Oct 13 Fixtures & Introduction of Studio project

8 Oct 20 Lighting Simulation I – Ecotect

9 Oct 27 Lighting Simulation II – Radiance

10 Nov 3 Lighting Simulation III – Radiance

11 Nov 10 Midterm project critique and introduction of final project parameters

12 Nov 17 Field Trip – tour of Montreal architectural lighting installations

13 Nov 24 Daylighting Techniques

14 Dec 9 Final Project Critique

Course Outline

Does the course web site work for everybody?

(online courses >> Electrical Services – Lighting ARCH 447)

Any questions on term project?

Take attendance.

Kristina Bondy & Daniel Juck: You should have access to ARCH software.

Request SketchUp/Form Z. Demo will follow in this lecture for SketchUp. FormZ demo in drop-in lab.

Square One shop closed until next Monday.

Misc

Sketch Up, FromZ,...Sketch Up, FromZ,...

EcotectEcotect

3ds file3ds file

Radtool (Radiance)Radtool (Radiance)

rad filerad file

Simulation Tools used in this Course

Sketch Up Installed on all ARCH computers.Sketch Up Installed on all ARCH computers.

Ecotect Installed on all ARCH computers. Site license, maximum number of five sessions at the same time.

Ecotect Installed on all ARCH computers. Site license, maximum number of five sessions at the same time.

Availability of Tools

Desktop RadianceInstalled on all ARCH computers.

Desktop RadianceInstalled on all ARCH computers.

Sketch Up Download from www.sketchup.comLicense issue unfortunately still unresolved.

Sketch Up Download from www.sketchup.comLicense issue unfortunately still unresolved.

Ecotect Download from Square One website. $US90 oer student licence (Windows only).

Ecotect Download from Square One website. $US90 oer student licence (Windows only).

Setting up your own computer (optional)

Desktop RadianceDownload from LBNL web site (Windows or Mac).

Desktop RadianceDownload from LBNL web site (Windows or Mac).

More details under:

online courses >> Electrical Services – Lighting ARCH 447 >> 1.2 software

(1) Installation Instructions on Course web site

(2) Download from LBNL web site

(3) Install preferably under “C:\Radiance”

(4) Set link in Ecotect

Install Desktop Radiance on your PC

• introduce some daylight performance metrics

• daylight factor calculations in Ecotect

• simulation models

• avoidance of direct sunlight

Objectives for this lecture

Daylight Performance Metrics

Review - Photometric QuantitiesCharacterize how a space is perceived.

Luminous Flux

LuminanceLuminous Intensity

Illuminance

Computer simulation: luminances and illuminances

Luminous Distribution, cd/m2

Luminance L (absolute brightness)

Photo

sunny summer day 70000 - 100000 lux

cloudy summer day 20000 lux

cloudy winter day 3000 lux

requirement for reading 100 lux

requirement for office work 300 - 800 lux

Review - Typical Illuminance Values

category material classification

example of materials

lighting illuminance

limiting annual exposure

I insensitive metal, stone, glass, ceramic

no limit no limit

II low sensitivity canvases, frescos, wood, leather

200 lux 600 000 lux h /yr

III medium sensitivity

watercolor, pastel, various paper

50 lux 150 000 lux h/yr

IV high sensitivity

silk, newspaper, sensitive pigments

50 lux 15 000 lux h/yr

Museum LightingCIE TC3-22 ‘Museum lighting and protection against radiation damage’

Review - Daylighting DefinitionsArchitectural definition: the interplay of natural light and building form to provide a visually stimulating, healthful, and productive interior environmentLighting Energy Savings definition: the replacement of indoor electric illumination needs by daylight, resulting in reduced annual energy consumption for lightingBuilding Energy Consumption definition: the use of fenestration systems and responsive electric lighting controls to reduce overall building energyrequirements (heating, cooling, lighting) Load Management definition: dynamic control of fenestration and lighting to manage and control building peak electric demand and load shape

Cost definition: the use of daylighting strategies to minimize operating costs and maximize output, sales, or productivity

**

*

Green Building Rating Systems I

LEED and Green Globe provide daylight credits for:

! daylight factor

! view to the outside

! specification of shading devices (Green Globe only)

Compliance is verified via spreadsheet method.

Do daylight factor & view LEED to good daylighting?

Daylight Factor Definition

E point

E outside horizontal

DF = (E point/E outside horizontal) * 100%

The DF is only defined under overcast skies!

Credit 8.1 Daylight 75% of Spaces 1 Credit• Archive a minimum Daylight factor of 2%

(excluding all direct sunlight penetration) in 75% of all space occupied for critical visual tasks. Spaces excluded from this requirement include copy rooms, storage areas, mechanical plant rooms, laundry and other low occupancy support areas. Other explanations for spaces where tasks would be hindered by the use of daylight will be considered on their merits.

Green Building Rating Systems II

Credit 8.2 Views for 90% of Spaces 1 Credit• Achieve direct line of sight to vision glazing for building occupants in 90%

of all regularly occupied spaces. Examples for exceptions copy rooms, storage areas, mechanical, laundry and other low occupancy support areas. Other exemptions will be considered on their merits.

Green Building Rating Systems III

Historical Background: “Right of Light”

Waldram 1945Waldram 1945

Daylight Factor Use in Design

Pro:! intuitive quantity! overcast sky as a worst case scenario! venetian blinds (even if closed) still admit sufficient DL

7%

3,5%

0%

Daylight Simulations in Ecotect

• Performance Metrics (daylight factor, avoidance of direct sunlight)

• Building Model

• Area of Interest (analysis grid)

• Sky Model

• Simulation Model

• Material Properties

Elements needed for a DL Simulation

Ecotect Demo - Prepare a simple model, add a grid, start a simulation

CIE clear sky CIE overcast sky

Overcast sky: zenith to horizon 3-1

Sky Models: CIE Sky Model

Square One web site

Design Sky values are derived from a statistical analysis of outdoor illuminance levels. They represent a horizontal illuminance level that is exceeded 85% of the time between the hours of 9am and 5pm throughout the working year. Thus they also represent a worst-case scenario that you can design to and be sure your building will meet the desired light levels at least 85% of the time.

Limitation in Ecotect. Climate files are not used by lighting simulation.

Design Sky Values

Average Daylight Factor (spread sheet method, similar to IESNA method)

Original Split Flux Method (Daylight Factor Protractors)

Points of Equal Sky Illuminance

Split Flux Method in Ecotect

Daylight Factor Calculation Methods

W = The area of each window (m²),

ττττ = Transmittance of each glazing material

θθθθ = Vertical angle of the sky as seen from the centre of each window

m = Maintenance factor based on angle of glazing and the cleanliness of its

environment (0.5 – 0.9),

A = Total internal surface area of the space, including walls, floors, ceilings and

windows (m²),

R 2= Area weighted average reflectance of all surfaces making up A, (use 0.1 as

reflectance for glass).

Average Daylight Factor Calculation

SC = direct component

ERC = externally reflected component

IRC = internally reflected component

DF= SC + ERC + IRC

UK Building Research Establishment (BRE)Split Flux Method

Daylight Factor Protractors

SC

ERC

Square One web site

Square One web site

DF = SC + ERC + IRC

= 1.52% + 0.0456% + 1.7586%

= 3.324 %

In Montreal:

Design sky = 7215 Lux

Light Level = 7215 Lux x 3.324%

= 240 Lux

Square One web site

Points of Equal Sky Illuminance

Square One web site

A geometric version of the Split Flux Method (BRE)

Raytracing: each ray represents an approximately equal solid angle of sky

Split Flux Method in Ecotect

Split Flux Method in Ecotect

Square One web site

A Sky Component (SC) is modified by:

• relative sky illuminance of that particular sky patch

•relative angle of sky patch makes with a horizontal surface

•visible transmittance of each glazing material through which it travels

Split Flux Method in Ecotect

Square One web site

An Externally Reflected Component (ERC) is modified by:

• luminance of the sky it would have hit

• reflectance of the material assigned to the external object

• relative surface angle and glazing transmittances

Split Flux Method in Ecotect

Square One web site

An Internally Reflected Component (IRC) is modified by:

• store internal surface reflectance of the object

• altitude angle of the ray is used to determine which parts of the IRC formula the ray contributes to.

Split Flux Method in Ecotect

Summing up over ray contribution and comparing it against the total

unmodified illuminance gives the Daylight Factor.

BRE Daylight Factor method uses a relatively simple formula for the effect of internal reflections. To be fully compliant with this method, Ecotect cannot consider multiple reflections. Therefore, Ecotect underestimates indirect daylight solutions that rely on the reflection of light off multiple surfaces to illuminate a space. Limitations of the sky model (Ecotect does not use annual climate file data for daylighting).

Limitations of the Ecotect Approach

Ecotect Demo – Open GL & parameter study

Daylight Factor – design implications window head height !!!!reference

glazing type !!!! narrow floor plan !!!!

Daylight Factor – design implications IIThe daylight factor optimized building is fully glazed.

Daylight Factor – design implications IIIDaylight factor does not take glare or solar gain control into account. The consequence of too large glazings:

The blinds are closed most of the time.

Avoidance of Direct Sunlight

Avoidance during cooling period (often assumed to be Apr 1st

to Oct 1st) or according to climate file. For Montreal: May 1st to Oct 1st.

Resulting building design form is improved from an energy standpoint.

optimized for static shading devicelouvers, lightshelves etc. !!!!

Assign Shaded As… Save As Bitmap…Open GL …

Ecotect Demo – Shading Analysis & design of a simple lightshelf

Ecotect Demo - import a SketchUp file

Material Propertiesvisual transmittance: windows, skylights, lightshelves

reflectivity of internal surfaces

external elements site obstructions and applied shading devices

Material Properties – Opaque Surfaces

specular reflectance

diffuse reflectance

mixed reflectance

For a perfectly diffuse

surface (Lambert surface)

holds:

E.g. paper, drywall

πρEL =

Material Properties

Ecotect Demo – Electric Lighting

(1) Submit your project proposals.

(2) Carry out a daylight factor and avoidance of direct sunlight analysis in an office building of your choice. Required minimum illuminance level: 300 lux. Avoid direct sunlight from Apr 1st to Oct 1st.

Assignments for next week

Questions…Questions…