Federation of European Heating, Ventilation and Air Conditioning Associations

Solar shading

REHVA Guidebook 12

presentation at 12th Annual Engineers

Association workshop Lisboa on Oct 25th

Originally prepared by Wouter Beck, Hunter

Douglas, editor of the Guidebook

Presented by Olli Seppänen

Member of the Solar Shading Task Force

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Author affiliations

• Wouter Beck, Hunter

Douglas, NL

• Dick Dolmans, ES-SO,

Belgium

• Gonzague Dutoo, Dickson

Constant, France

• Anders Hall, Somfy Nordic,

Sweden

• Olli Seppänen, Finland,

(REHVA)

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Task force Solar Shading

started 2008

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Table of Contents • Terminology

• Solar radiation

• Effect of windows on indoor environment

• Window systems

• Energy effects of solar shading

• How to choose a shading solution

• Automating and integrating solar shading

• Existing buildings

• Double-skin facades

• Maintenance of solar shading systems

• Cases

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Solar radiation

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Solar radiation

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Solar angles Lisboa 39, Porto 41degrees N

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Solar irradiance on a façade

(lat. 50 N, clear sky)

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Solar irradiance on a façade

(lat. 50 N, clear sky)

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Solar irradiance on a façade

(lat. 50 N, clear sky)

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Effect of windows on indoor

environment

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Effect of windows on indoor

environment

• Thermal comfort

• Visual comfort

• Acoustic comfort

• Indoor air quality

• Daylighting

• Impact of productivity

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Thermal comfort

• Air temperature

• Radiant

temperature

• Operative

temperature

• Relation to

office

worker

productivity

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Visual comfort

• Contact with the outdoors

• Absolute brightness

• Luminance ratios

• Color rendition

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Effect of good visual comfort

• 3.75% median productivity increase [CMU]

• 20 to 25% less health complaints [Hartkopf]

• 15% reduced absenteeism [Thayer]

• 10 to 25% better performance on test of mental function

• 20 to 26% faster progress of students [Heshong]

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Too high difference in

luminance

Photo Somfy

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Solar shading reduces the

differences aceptable

Photo Somfy

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The economic impact of

productivity

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Window systems

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Energy flows

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Glazing properties depend on the

wave lenght • Thermal transmittance U [W/m2K]

• Light transmittance Tv [-]

• g-value [-]

• T=transmittance, R=reflectance, A= absorbtance

Standard double galazing Solar control glazing

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Indicative properties

convection loads

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Cooling loads – no shading

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Cooling load – exterior shading

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Surface temperature interior window pane

under peak load conditions – no shading

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Surface temperature interior window

pane under peak load conditions –

exterior shading

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Energy effects

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Energy effects of solar

shading

• Orientation dependent energy balance of an office for

• Stockholm

• Amsterdam

• Madrid

• Three glazing types

• Standard double glazing (U = 2.9 W/m2K)

• Low-e (U = 1.2 W/m2K)

• Solar control glazing (U = 1.1 W/m2K)

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Standard office • dimension 3.6 x 5 x 3 m

• ventilation 1.5 dm3/m2s

• infiltration 0.1 ACH

• daylight dependent lighting 500 lx

• max. internal load art. lighting 12 W/m2

• internal loads people 10 W/m2

• internal loads equipment 15 W/m2

• thermostat cooling 25/30 ºC (8-18/otherwise)

• thermostat heating 21/15 ºC (8-18/otherwise)

• shading set point 200 W/m2

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Effect of solar shading on energy use,

Madrid weather data

Green=primary energy, blue=heat removed from room,

red=heating of room, yellow=elctricity for lighting

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Cooling load reduction by

solar glazing and shading

Cooling load for a model office in Madrid, Spain (latitude 40 degrees north ) depending on

window orientation. Solid lines represent cooling loads without shading and the broken lines

with external venetian blind shading. Red lines represent clear double glazing (g=0.75),

yellow low-e glazing (g=0.64) and blue solar control glazing (g=0.32).

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std. double

low-e

solar ctrl

Reduction in primary energy use for heating,

cooling and lighting through shading, Madrid

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Cost benefit analysis of solar

shading, Madrid weather

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Cases

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Trafalgar House, Croydon

Concrete Walls

Anti-Glare Blinds Internally

Rain Screen

CladdingExtract Duct

Exposed Concrete Slab

Radiators Supply Duct

Automatic

opening vent

behind

louvres

Automatic

opening

window

Aerofoils

Concrete Walls

Anti-Glare Blinds Internally

Rain Screen

CladdingExtract Duct

Exposed Concrete Slab

Radiators Supply Duct

Automatic

opening vent

behind

louvres

Automatic

opening

window

Aerofoils

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Appendices

• EU standards concerning shutters

and blinds

• Specification example

• Matrix of responsibilities

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Reviewers

• Prof. Jan Hensen, Eindhoven University of Technology, The Netherlands

• Prof. Mat Santamouris, University of Athens, Greece

• Hervé Lamy, SNFPSA, Paris, France

• Prof. Michael G Hutchins, Sonnergy Ltd, Abingdon, UK

• Dr. Thanos Tzempelikos, Purdue University, West Lafayette, IN, USA

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Acknowledgements

• Ellen Kohl (Warema),

• Maaike Berckmoes (Scheldebouw-Permasteelisa),

• Risto Kosonen (Halton),

• Bernard Gilmont (European Aluminium Association),

• Maija Virta (Halton),

• Prof. Dirk Saelens (Catholic University of Leuven, Belgium

• Prof. Zoltan Magyar (University of Pécs, Hungary)