TEST LOCATION & METHODOLOGY:Full-scale testing is conducted at the Iowa Energy Center’s Energy Resource

Station in Ankeny, IA with 3 sets of parallel test rooms

Civil, Construction and Environmental Engineering | Mechanical Engineering | Architecture

Students: Niraj Kunwar, Yoann Gorostiaga Faculty: Kristen S. Cetin, Ulrike Passe

Effect of Dynamic Shading Devices on Daylighting and Energy Performance of Perimeter Office Zones

OBJECTIVES:The main objective of this research is to evaluate the

effectiveness and energy savings potential of several types of

commonly used dynamic shading devices coupled with

electric lighting control in perimeter office spaces with

different types of glazing systems through full-scale

experiments and testing.

Full-scale experimental testing & data collection: Test

dynamic roller shades and venetian blinds in a perimeter

office space;

Method for evaluation of energy savings potential and occupant

comfort: Develop a methodology that can be used to

evaluate the energy savings potential of a combination of

dynamic shading devices and lighting controls;

Development/testing of control algorithms: Develop and test

control algorithms that control lights and shading devices

to achieve energy savings and maintain a comfortable

environment for occupants.

BACKGROUND:Commercial buildings (primarily office buildings) are

responsible for a large amount of the 40% and 72% of energy

and electricity consumption from buildings.

Modern office buildings have a strong potential for energy

savings (Poirazis et al 2008) but must also provide thermal and

lighting comfort to occupants to facilitate a productive work

environment.

Dynamic shading and lighting devices have been developed by

various companies in attempt to conserve energy, however

there has been limited full-scale controlled testing to

understand what the measured energy and occupant comfort

benefits are of these devices

Energy use and occupant comfort are significantly impacted by

the following, all of which are tested in this work:

- Orientation of the building façade(s)

- Type of window

- Type of shading device

- Type of control strategy

CURRENT STATUSContinue conducting tests at the ERS for different combinations of windows, shading

devices, control strategies, and times of the year

Location of full-scale experimental testing including (a) exterior, (b) interior layout

(a) (b) (a)

PRELIMINARY RESULTSNormalization testing was conducted first to ensure the parallel test rooms are equal

Energy Savings:

Visual Comfort: Vertical Illuminance & Daylight Glare Probability (DGP)

Visual Comfort: Workplane Illuminance & Distribution

Workplane illuminance

Vertical illuminance

Set Point Value ReferenceHorizontal

illuminance height0.8 m Shen,Tzempelikos (2015)

Vertical illuminance

height1.2 m

Chan, Tzempelikos 2015,

Konstantzos (2015)Horizontal

illuminance

distance from

window

1m,2.5m

,4mlocation utilized varies by study

Vertical illuminance

distance from

window

2.75mAssuming person to be 0.5 m

from the workplane at 1m

Name Color U-value VT SC

Window A Clear/Clear 3mm glass; air space 0.55 81% 0.85

Window BLow-e 366 side 2/Clear 3 mm glass;

0.462” 90% Ar/10% Air space 0.24 65% 0.274

Window Properties

ShadesOpenness

Factor

Visible

Transmittance

Solar

Transmittance

Solar

Absorptance

Solar

reflectanceColor

Roller Shades 1 1 % (approx.) 1% 1% 95% 4% Charcoal

Roller Shades 2 3% (approx.) 12% 17% 19% 64% Oyster

Shading Device Properties

Shades Slat Size Material Tilt Angle Solar Reflectance Emissivity Color

Blinds 2 in Aluminum -90 to 90 70% 0.76 Beige

Glare and Light Level Monitoring

0

100

200

300

400

500

600

6:00 9:00 12:00 15:00 18:00 21:00 0:00

Pow

er (

W)

Time of Day

West A Lighting Power (W) Max at 500 lxWest A Lighting Power (W)West B Lighting Power (W)

0

0.5

1

1.5

0

500

1000

1500

2000

6:00 9:00 12:00 15:00 18:00 21:00

Shad

e H

eight

(m)

Ver

tica

l Il

lum

inance

(lu

x)

Time

West A - Vertical IlluminanceWest B - Vertical IlluminanceWest B - Shade Height

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

6:00 9:00 12:00 15:00 18:00 21:00

Shad

e H

eight

(m)

Day

lig

ht

Gla

re P

rob

abil

ity

(DG

P)

Time

West A - DGPWest B - DGPWest B - Shade Height

0

0.5

1

1.5

2

2.5

0

500

1000

1500

2000

6:00 9:00 12:00 15:00 18:00 21:00

Sh

ade

Hei

gh

t (m

)

Work

pla

ne

Illu

min

ance

(lu

x)

Time

West A - Workplane Illuminance (2.5 m)

West B - Workplane Illuminance (2.5 m)

West B - Shade Height

0

1000

2000

3000

4000

6:00 9:00 12:00 15:00 18:00 21:00Work

pla

ne

Illu

min

ance

(lu

x)

Time

West A - 1 m (Rmlite 2)West A - 2.5 m (Rmlite1)West A - 4.5 m (Rmlite 5)West A - ceiling sensor (2.6 m) (Rmlite 4)

Preliminary testing indicates energy savings is achieved due to

both HVAC and lighting energy reduction in most

cases/combinations. For example:

Lighting:

5.75 kWh in Test Room A and 4.56 kWh in Test Room B,

achieving an energy savings of 20.6%

Use of the dynamic

shading and lighting

controls reduces the

high levels of vertical

illuminance, hence

preventing glare,

when glare is said to

occur when threshold

of DGP (daylight

glare probability) is

reached.

Illuminance at the

workplane sensor

near the window is

highest. The

illuminance value

decreased the farther

the distance from the

window. The ceiling

value was lowest.