Benefits of building thermal insulation on HVAC system sizing and PV penetration
Summary of Graduation Project The graduation project aimed, by using ecotect software, to determine the optimal thickness of two types of thermal insulation; expanded and extruded polystyrene, and choosing the best of them to be added to the construction layers of the external walls and roof of a villa in Jerusalem with a floor area of 241 m2. The best type of the thermal insulation was extruded polystyrene with an optimal thickness of 9 cm for external walls and roof, and with an initial cost of 15 223 Nis. It also studied the saving in HVAC system capacity cost and its yearly operating cost resulted due to that optimal thickness of extruded polystyrene use instead of not using insulation scenario, where; the initial cost of HVAC system was 35 900 Nis with saving in initial cost due to saving in capacity was 8975 Nis, the cost of double glass was 61 852 Nis and the annual saving in operating cost was 6 411 Nis/year that led to obtain 8 years simple payback period. After that, design of a photovoltaic system was required to determine how much the PV system would feed the need of HVAC load according to the available roof area, 110 m2. However, the installed PV panels only can feed approximately 50% of HVAC load in the optimal thickness of insulation case that has a load of 100 kWh/day, while in without insulation case that has a load of 126.6 kWh/day, the installed PV panels can feed only 39% of HVAC load. Because of the penetration level of 50%, the system was installed on grid not off grid system, because there will be no excess of power to be stored in batteries. The investment of this project included cost of solar panels with installation, inverter, cables as well as annual cleaning and estimated as 27 080 Nis, and with 11 668 Nis/year annual saving in operating cost resulted due to reduction of electricity consumption from 23 625 to 11 957 Nis /year, the simple payback obtained was approximately two years.