Characterisation of solar control properties

compliant product data

Wouter Beck

Ascendilexwww.daglichtontwerp.nl

Earth

The sun

Largest free energy flux on Earth

Essential for all life on earth

There’s a good cause for daylight and views

• Best quality light

• High luminous efficacy

• Most people prefer daylight

• Increases productivity and learning results

• Reduces absenteism, length of hospital stay

• Keeps our circadian rhytm in sync

“Using sunlight and daylight is like

trying to drink from a fire hydrant: the

challenge is CONTROL”

Stephen Selkowitz, LBNL

6

Compliant

product data

Why compliant product data?

EPBD requires amongst others:

• Methodology for the calculation of the energy performance of buildings (new builds, retrofits)

Modelling thermal comfort:

• Determine temperature exceedances

• Determine thermal comfort according to ISO 7730 and similar norms

Why compliant product data?

Dynamic Energy Modelling:

• Engineering the energy requirements of a building –optimise the balance of comfort, energy reqmts. andequipment size

All of these computational approaches rely on reliableinputs for the physical properties of building materials

• Rubish in is rubish out

• Need for compliant data obtained throughstandardised and clear procedures

Characterisation

of fenestration

Characterisation of fenestration

High level characterization:

• U – thermal transmittance [W/m2K]

• g – total solar transmittance [-]

• Tv – visual light transmittance [-]

In some countries:

• Fc = gtot/gglass : shading factor [-]

Normative

context

• EN 673 – Glass in building - Determination of thermal transmittance

• EN 410 – Glass in building - Determination of luminous and solar characteristics of glazing

• EN 14500 – measurement

• EN 13363-1: Solar protection devices combined with glazing. Calculation of solar and light transmittance. Simplified method

• EN 13363-2: Solar protection devices combined with glazing. Calculation of total solar energy transmittance and light transmittance. Detailed calculation method

• ISO 15099: Thermal performance of windows, doors and shading devices – Detailed calculations

EN 13363-1 (Simplified method)

• Can be done in a spreadsheet and requires:• integrated transmittance and reflectance data of shading

• U- and g-value of glazing

• Outcomes are generally conservative (on the high side, especially for interior shading)

EN 13363-2 and ISO 15099

• Requires computer program to solve the nonlinear energy balance. Requires:

• Spectral transmittance and reflectance data of both shading and glazing layers

• IR transmittance and emissivities

• Thermal conductivities and gasses

• Geometric data: thickness, distance, ventilation

• Various codes available: WIS, WinSLT, Physalis, …

EPBD

EPBD requirement

• Methodology for the calculation of the energy performance of buildings (new builds, retrofits)

• EN ISO 13790 – Energy performance of buildings

• Various supporting EN standards

• National Calculation Methods in each MS, some of which are based on EN 13790

EN 13790 Energy performance of buildings

Chapter 11 deals with solar heat gains

Section 11.4.3: Movable shading provisions

• ggl+sh : total solar energy transmittance of window when solar shading is in use

• ggl+sh is often referred to as gtot: the solar factor of glazing and shading combined

• The solar factor is the proportion of incident solar energy that ends up on the inside of a fenestration system

Shading in national EPB calculation methodologies

Country Shading in BC or EPB Methodology

Austria Prevention of overheating Fc = 0.15/0.25/0.5 or 13363 g-value

Belgium Prevention of overheating Fc = 0.50/0.60/0.9 or accredited value

Denmark yes Actual g-value, automatic/manual

Finland yes

France detailed At least 24 actual values, aut./man. …

Germany yes, DIN 4108-2, 18599 Actual Fc value

Greece

Hungary Prevention of overheating

Ireland no

Italy Yes, UNI 11300 (13790) Actual g-value, ext.

Malta yes

Shading in national calculation methodologies

Country Shading in BC or EPB Methodology

Netherlands Yes, NEN 7120 (13790) Ext: Fc = 0.3

Norway Yes

Poland Yes Default values

Portugal Yes

Spain Yes Actual g-value

Sweden No (no EPB calculation) Dynamic Simulation

Switzerland Yes

UK Yes Default g-values

Shading is a European technology, but No harmonisation Default values often far from actual values Use compliant data for EPB !

French RT2012 (Réglementation Thermique)► Characteristics of products

Thermal transmittance (Uw)

Without protection With protection

French RT2012► Characteristics of products

Solar factor (Sw)

Without protection With protection

Exte

rnal

Inte

rnal

French RT2012► Characteristics of products

Light transmittance(Tlw)

Without protection With protection

French RT2012

• To characterise a glazed surface with a solar protection

device other than a Venetian blind:

• 4 Uw values are needed,

• 6 Sw values are needed,

• 4 Tlw values are needed.

• When the glazed surface is equipped with a Venetian

blind :

• 4 Uw values are needed,

• 54 Sw values are needed,

• 24 Tlw values are needed.

Dynamic Energy Simulation Codes

• EnergyPlus and many commercial codes

• Treatment of windows and shadings differs

• In the better codes, energy transfer through window and shading is determined at each time step by solving some variation of the ISO 15099 equations

• Input varies from g-values to full spectral data sets and other thermo-physical data

ESS-DA provides all data needed to facilitate these simulations (exception: BSDF-data for CFS)

EN 14501• Glare control

• Visual contact with the outside

• Night privacy

Tv,n-n (direct) light through the holes

Tv,n-dif (diffuse) brightness of the screen itself

Outdoors Indoors

ESS-DA provides spectral direct and diffuse transmittance data

• ESS-DA provides complete base data from which • g-values• Visible reflectance and transmittance• Thermal transittance (U-values)• Visual comfort descriptors

for windows fitted with solar shading can be determined using EN and ISO norms

• ESS-DA can feed all national calculation methodologies

• ESS-DA can feed all dynamic energy simulation codes

• All ESS-DA data is validated and peer reviewed

The sole responsibility for the content of this presentation lies with the authors. It does not necessarily reflect the opinion of the

European Union. Neither the EASME nor the European Commission are responsible for any use that may be made of the

information contained therein.