Simple Calculation Method Project Overview WP1: State of the Art WP2: Non-techno-logical Barriers WP3: Benchmarks and Certification WP4: Simple Calculation Method WP4: Simple Calculation Method WP5: Best Practice Guidelines WP6: Dissemination

Why a Simple Calculation Method for Double Skin Facades? Present situation: assessment of thermal behaviour and energy efficiency of naturally ventilated DSF is only possible by using complex simulation tools interconnections between fluid dynamics, energy balances, and optical mechanisms -> iterations are necessary impossible to have reliable predictions on energy efficiency and impact on comfort in the early planning stage BESTFACADE is developing an assessment method that can be integrated in the national calculation methods of the EPBD with sufficient accuracy of thermal behaviour and the energy performance

Analysed (Standard) Approaches prEN/ISO 13790 - Energy performance of buildings ISO/FDIS 13789 – Thermal performance of buildings DIN V 18599 – German standard for EPBD calculations Platzer approach – modified prEN/ISO 13790 WIS approach – EU project WinDat EN 13830 – Curtain walling prEN 13947 – Thermal performance of curtain walling with ventilated and unventilated air spaces ISO 15099 – Thermal performance of windows.... ISO 18292 - Energy performance of fenestration systems - Calculation procedure does not yet foresee the calculation of DSF no consideration of solar radiation similar to wintergarden in prEN/ISO 13790, solar radiation model includes weaknesses ( ) stationary calculation, requires a computer tool and various input data only definitions, no calculation procedures only calculates the reduced transmission losses (buffer effect), no influences on solar gains only thermal characteristics, no energy, no coupling to building ( ) facade rating, can be used for DSF

The Application of DSF in the DIN V 18599 DIN V 18599 follows the philosophy of the prEN/ISO 13790: holistic calculation DSF constructions are a subsystem of unheated glazed annexes The solar heat gains in the building zone are calculated as: QS,tr = FF,iu * Aiu * geff,iu * FF,ue * e,ue * IS * t The heat flow through the glazed annex or conservatory must be calculated in order to determine the temperature in that space. The solar radiation entering the annex or conservatory must be calculated using equation  S,u = FF,ue * Aue * geff,ue * IS DIN V 18599 demands to use an air change rate nue = 10 h-1

Further Development of the Simplified DIN V 18599 Approach within BESTFACADE more detailed approximation of the ventilation rate in the air gap air flow rate will take into account the facade geometry and the temperature difference based on measured data from: - BiSoP Baden (IWT) - VERU Holzkirchen (Fraunhofer-IBP) - Postcheque building, Vliet test building, Aula Magna building (BBRI) Validation: use of different models like WIS, Energy Plus and Parasol

Characteristic values based on measurements: BiSoP

Characteristic values based on measurements: VERU

Characteristic values based on measurements: VERU

Characteristic values based on measurements: VERU

Characteristic values based on measurements: VERU

Default ventilation rates Façade control strategy (Default) air change rate [h-1] Summer (April–Oct.) Winter (Nov.–March) Open at all times 25 Adjustable flaps 4

Application of the Method in an internet-based Information Tool DSF information tool for the first planning stage use of an existing environment developed at Fraunhofer-IBP further development is a cooperation between different partners in BESTFACADE will allow the energy performance assessment for heating, cooling, ventilation and lighting of a standard room behind a DSF lighting: prEN 15193-1 with DIN V 18599-4 (facade performance)

Available on the BESTFACADE website: www.bestfacade.com