Applying architecture simulation tools to assess building sustainable design: Adapting the Egyptian residential energy code for climate change

In Egypt, residential and commercial buildings energy consumption has been increasing to more than 44% of the total energy consumption, partly due to Egypt’s rapid increase in population, which led to the aggravation of the energy crisis. Building energy codes have recently become an effective technique to enhance energy efficiency in buildings, as regulating the buildings' energy performance ? via energy standards ? can be regarded as an effective means to reduce energy consumption.

This research focuses on improving the energy performance of the building envelope, using the principles of environmental design, in the hot-arid climatic context of Egypt, aiming to reduce the energy consumption in the residential sector. This will reflect on reducing the use of HVAC systems, subsequently reducing the energy running costs and the corresponding CO2 emissions. This is carried out through studying the building envelope section in the Egyptian Residential Energy Code (EREC). The work focuses on the residential sector, as in almost every country this is the major energy consumer, and more specifically, the large housing projects. In order to identify the validity of EREC under future climate change, the research aims to study the different design solutions and construction methods recommended by the code or commonly used in the building industry sector in Egypt and evaluate them under the different climate change scenarios to identify the climate change effects on the indoor thermal comfort, the energy consumption and the financial implications (investment vs. running costs). The Buildings' thermal performance simulations (BPS), was adopted as the major technique in the research.

The BPS tool "EnergyPlus" and its architectural friendly interface "DesignBuilder" were used to simulate the buildings thermal behaviour in the different climatic periods, in order to assess and modify EREC to adapt to the future climate change effects. The future weather data files, which represent the climate change conditions, were generated via the morphing technique, using the Climate Change World Weather File Generator tool (CCWorldWeatherGen). Moreover, a long term financial analysis method was employed to relate the theoretical study to the real world, based on the financial theory of Discounted Cash Flow (DCF) and its practical formula Net Present Value (NPV), to produce an accurate estimation of the financial efficiency of the projects.

The research outcomes are considered as an attempt to highlight current limitations of the residential energy code, especially in its behaviour against climate change. The results focus on energy consumption reductions for the residential units, along with financial benefits on the long term, while maintaining the indoor thermal comfort conditions using active and passive techniques. Through the results analysis, it was found it is not necessary to use the most expensive materials and techniques in order to achieve the most effective thermal insulation, as there are some cheaper materials and techniques in the Egyptian market, more beneficial and cost effective over the long term (under future climate change scenarios). The results have proven that, only two parts of the code's recommendations are compatible with the predicted climate changes on the long term (fenestration and shading devices), and they can mitigate the associated temperatures increase and could continue to be used efficiently through the prescriptive approach in the code. While the code's recommendations for the external walls' specifications, was found to be inadequate and inefficient over the long term. Thus, the study recommends not to use the code's prescriptive approach to determine the external walls' thermal specifications, and to use the code's overall performance path instead. In addition, the research has provided what seems to be the optimum and the most cost-effective combination of specifications to be used (in three different climatic zones), in order to achieve the best levels of performance in terms of indoor thermal comfort levels and energy consumption reduction for the project over the long term. The results are likely to be of interest to a wide range of designers, architects and to support both policy and decision makers taking steps forward towards energy efficiency obligations, particularly in Egypt.