In the light of increasing the world energy demand, the historical buildings attained international concern, since they have significant value that requires to be protected. For instance, building sector in Egypt consumes about 42% of the national energy consumption \citep{Fahmy_2014}. In Europe, building sector is responsible for consuming 40% of the total energy consumption and 10% of the total CO2 emissions \citep{Serghides_2015}. So, several conventions are developed to reduce energy demands in the building sector (exiting and new) including the historical ones such as 2030 energy strategy in EU.
Dealing with energy saving in historical buildings requires a certain attention for conserving their cultural significance and heritage value. This is the reason behind issuing the first law in EU so called “Conservation of cultural heritage – Guidelines for improving the energy performance of historic buildings- FprEN16883”. Also, 3ENCULT & EFFESUS are examples for projects that have studied the balance between energy efficiency, thermal comfort and conservation requirements in the historic buildings stock in the EU. The results of studies have been carried out in Sweden to balance between the energy conservation and building conservation have shown that 20% of energy saving can be achieved without damaging the cultural heritage value \citep{_ahin_2015}.
However, the same question remains, “is it possible to achieve balance between thermal comfort requirements and conservation issues in other climate regions such as hot arid zones?”
In the other countries such as Egypt, the links between the cultural heritage, thermal comfort and energy saving requirements are still missing. Although, the historic buildings in old Cairo area constitute large portion of the built environment as per URHC maps. These buildings are very valuable in terms of heritage and they also deal with environmental issues. Ottoman houses give example on this kind of valuable buildings. So, preserving these houses must respect the original culture significance and the recent conservation issues.
Balancing between conservation and thermal comfort requirements has to be applied to maintain the cultural heritage and to develop the technologies to meet the historical building’s needs. So, the debate about this topic shall be performed through theoretical, analytical, and practical studies.
RESEARCH QUESTION
Is it possible to achieve balance between the thermal comfort requirements and conservation requirements in the naturally ventilated historical buildings in hot arid zones?
CONCEPTUAL FRAMEWORK
Thermal comfort requirements and building performance issues in the historic buildings require multidisciplinary approach concerned with buildings that were designed in a specific period for a certain function to meet the need of their inhabitants and protect them from the climate conditions at that time. As time passed on, these buildings became an essential source of information about the history but in order to maintain these buildings the need of the current community and current climate conditions should be evaluated. Analysing the variables in this topic should be carried out in order to evaluate if it is useful to restore the natural ventilation system nowadays or it is better also to consider additional solutions to preserve architectural heritage and building use. Figure (1) shows simply the main variables in balancing between cultural heritage and thermal comfort requirements. The conservation issues and building energy performance issues will be discussed in this part.