TWO TYPES OF SHUTTERS - ONE FOR EXISTING BUILDINGS AND ONE FOR NEW BUILDINGS - HAVE BEEN CONSTRUCTED AND CONSIST OF POLYISOCYANURATE CELLULAR PLAST FOAM (PIR) WHICH HAS A VERY LOW THERMAL CONDUCTIVITY. SPECIAL ATTENTION HAS BEEN PAID TO THE JOINTS AROUND THE SHUTTERS TO SECURE A HIGH LEVEL OF AIR-TIGHTNESS. BOTH SHUTTERS HAVE TO BE REMOVED DURING DAYTIME. FOR EXISTING BUILDINGS INTERNAL SHUTTERS HAVE BEEN CHOSEN WHICH CONSIST OF 30 MM PIR. WHEN USED IN FRONT OF A DOUBLE GLAZED SEALED UNIT THE U-VALUE WILL BE REDUCED FROM 2.5 W/M2 DEGREE TO 0.67 W/M2 DEGREE (MEASURED VALUES). THE ANNUAL ENERGY SAVING WILL BE ABOUT 70 KWH/M2 (120 M2 HOUSE WITH 20 M2 WINDOW AREA) CALCULATED BY MEANS OF THE DEGREE DAY METHOD. AN ECONOMICAL ANALYSIS INDICATES THAT THE PIR-FOAM MUST HAVE A LIFETIME OF ABOUT 10 YEARS TO MAKE THE INVESTMENT COST-EFFECTIVE.

HUMIDITY TESTS HAVE BEEN MADE IN THE CLIMATIC CHAMBER AND UNDER NORMAL WINTER CONDITIONS THE DOUBLE GLAZED SEALED UNIT WILL SHOW SOME MINOR CONDENSATION WHEN THE SHUTTER IS REMOVED. THIS CONDENSATION WILL VANISH IN HALF AN HOUR. UNDER SEVERE WINTER CONDITIONS CONDENSATION IS MORE SERIOUS.

FOR NEW BUILDINGS SHUTTERS HABE BEEN DEVELOPED WHICH ARE LOCATED BETWEEN TWO LAYERS OF GLASS AND CONSIST OF 30 MM PIR. THE U-VALUE IS CHANGED FROM 2.1 TO 0.91 W/M2 DEGREE (MEASURED VALUES) BY USING THE SHUTTERS AND THE ANNUAL SAVINGS WILL BE ABOUT 45 KWH/M2. COMPARED TO A NORMAL DOUBLE GLAZED SEALED UNIT THE SAVINGS WILL BE ABOUT 75 KWH/M2 PER YEAR, AS THE SAVING FROM 2.5 W/M2 DEGREE (WHICH IS THE U-VALUE OF A NORMAL DOUBLE GLAZED SEALED UNIT) TO 2.1 SECURES AN ANNUAL ENERGY SAVING OF APPROX 30 KWH/M2. A LIFETIME OF ABOUT 20 YEARS IS NECESSARY FOR THE ELEMENT TO BE COST-EFFECTIVE.

THE TESTS IN THE COLD/HOT BOX HAVE SHOWN THAT UNDER NORMAL WINTER CONDITIONS THERE WILL BE NO CONDENSATION PROBLEMS. AS IT IS NECESSARY TO OPEN THE INNER PANE FOR MANUAL OPERATION OF THE SHUTTERS THERE WILL BE CONDENSATION ON THE OUTER PANE WHEN SEVERE WINTER TEMPERATURES OCCUR.