Dr. Mostafa Nejatolahi, Dr. Saeed Ghobadpouri, Mr. Ali Adnani,
Volume 5, Issue 1 ((Spring and Summer) 2024)
The simultaneous use of a large number of air-conditioning units in hot regions has driven Iran’s summer peak electricity demand beyond the capacity of the national grid, resulting in scheduled hourly power outages in buildings and industries. In response, the government is pursuing an increase in electricity-generation capacity through the construction of new gas-fired, nuclear, and solar power plants. Alongside this supply-side approach, reducing building cooling loads can reduce electricity demand during peak hours and thereby help alleviate pressure on the grid. Wall insulation and the installation of double-glazed windows are among the most important measures for improving the thermal performance of building envelopes, as they reduce heat transfer through the envelope and, consequently, cooling loads and summer electricity demand. However, low energy tariffs reduce building owners’ economic incentive to implement these measures. Therefore, this study evaluated their effects on the energy consumption of a residential building in Gachsaran, a city in a hot climate, using actual utility bills and hourly simulation in DesignBuilder. Polystyrene insulation thicknesses ranging from 1 to 20 cm were evaluated. The 3-cm-thick insulation layer had the shortest payback period and was therefore selected for comparison with double-glazed windows. The simulation results showed that the building’s annual peak cooling load occurred at 13:00 on 4 July. At this time, both measures reduced peak electrical demand by approximately 9%. However, wall insulation reduced annual cooling electricity consumption by 9.1%, compared with 7.45% for double-glazed windows. In addition, the initial cost of insulation was 36.6% lower, while its annual financial savings were 25.3% higher than those of double-glazed windows. Furthermore, by reducing winter heating loads, wall insulation can reduce natural-gas consumption, help maintain gas supply to gas-intensive industries such as cement plants, and reduce the use of mazut in power plants.
