Contemporary Engineering Sciences, Vol. 13, 2020, no. 1, 187 – 198 HIKARI Ltd, www.m-hikari.com https://doi.org/10.12988/ces.2020.91572 Optimisation of Heat Loss in Cities in Different Climatic Zones in a Mediterranean Climate Roberto Alonso González Lezcano Escuela Politécnica Superior, Universidad CEU San Pablo Montepríncipe Campus, 28668, Boadilla Del Monte, Madrid, Spain Eduardo José López Fernández Escuela Politécnica Superior, Universidad CEU San Pablo Montepríncipe Campus, 28668, Boadilla Del Monte, Madrid, Spain Sonia Cesteros García Escuela Politécnica Superior, Universidad CEU San Pablo Montepríncipe Campus, 28668, Boadilla Del Monte, Madrid, Spain Gastón Sanglier Contreras Escuela Politécnica Superior, Universidad CEU San Pablo Montepríncipe Campus, 28668, Boadilla Del Monte, Madrid, Spain This article is distributed under the Creative Commons by-nc-nd Attribution License. Copyright © 2020 Hikari Ltd. Abstract This article presents a study of different housing blocks in the city of Soria and Cadiz Spain, in which effective interventions are carried out not only for energy savings within the requirements of the Technical Building Code in Spain, but also for system saving in the short term. Various thicknesses of several types of insulation are analyzed, evaluating the resulting energy savings for each case, but not without leaving aside the economic aspect of the installation; and obtaining asymptotic values, in which the marginal cost of the investment will not be as variable. The article tries to exemplify how, by means of small interventions, savings could be high. They can be applied in many different types of buildings and contribute to reduce the demand of energy; is a breakthrough in the study of