Method for Determining the Optimum Insulation Thickness of the Plaster Tow Material: Influence of the Heat Exchange Coefficient in Transient Regime

In this paper, we have applied a numerical method to determine the optimum insulation thickness of the tow plaster plane material. The influence of the exchange coefficients at the level of the two faces of the material has been highlighted. The optimum insulation thickness of the material is at the area where the thermal resistance value of the material is the maximum. We added the relative thermal resistance to show how the optimum insulation thickness changes when the exchange coefficients change values.

Lifecycle Cost Analysis of An Insulated Duct With An Air Gap

The insulation materials are used to reduce heat loss to/from the ducts with additional investment. This study aims to reduce this additional investment in the duct application by introducing an air gap between insulation and duct surface. It uses Life Cycle Cost (LCC) analysis to determine the economic benefits of the air gap considering four insulation materials for insulating the duct and natural gas as an energy source for chiller operation. The preliminary data regarding design and operating parameters were obtained from a renowned pharmaceutical company. The duct's annual energy loss was estimated for given operation hours in a year using the preliminary data and ambient conditions. The estimated energy loss through the duct is fed in LCC analysis to determine the impact of the air gap on optimum insulation thickness corresponding to the minimum LCC and payback period. The results show that the introduced air gap in an insulated duct lowers the optimum insulation thickness for the duct. As a result, the air gap maximizes the cost savings and minimizes the payback period. The expanded polystyrene is investigated as the most economical with maximum cost savings of USD 508.8-USD $766.8/m/year and a payback period of 1.15–1.17 years for the duct applications. Contrary, the air gap is determined the most effective in terms of cost and emission savings for the ducts insulated with rock wool. In conclusion, an air gap is an economical option for duct applications.

Optimizing thermal insulation of external building walls in different climate zones in Libya

An efficient way to reduce the energy required for conditioning buildings and therefore to reduce CO2 emission is the use of proper thermal insulation in buildings’ external walls. This measure requires data from metrological stations that can be used in the optimization of the thermal insulation. The main objectives of this study are to construct thermal climatic zones for Libya and to specify the optimum insulation thickness for external walls for the different zones. This work is comprehensive as the metrological data from all existing 33 weather stations has been collected and used for identifying thermal zones. For the optimization of the construction of external walls, the most commonly used local wall structures are investigated: hollow concrete block, limestone block and hollow brick. In addition, four thermal insulation materials: extruded polystyrene, expanded polystyrene, rock wool and foamed polyurethane are used with every wall type. Optimum insulation thickness, energy savings, energy cost and payback periods were estimated for the 33 locations using life cycle cost analysis. A map is constructed for the thermal zones based on degree-day values for the entire country. The results show that limestone blocks with expanded polystyrene insulation form the optimum wall construction as it provides the minimum total cost for all locations. Depending on the Degree-day values, the optimum insulation thickness varies between 5.4 and 15.3 cm across the country with energy saving varies between 28 and 178 $/m2. Using the optimum thickness, the average CO2 emissions can potentially be reduced by about 85%. Finally, a contour map represents the optimum thickness of expanded polystyrene is presented in this work.