High performance thermal insulating composite materials can be produced with mineral binders and hydrophobic aerogel particles through a hydrophilization process for the latter with surfactants. The present study is focused on the development of aerogel/calcium sulfate composites by the hydrophilization of hydrophobic silica aerogel particles through a polymer-based surfactant. Its effects on the microstructure and hydration degree are examined as well as their relation to the resulting mechanical and physical properties. Results show that composites with an around 60 % of aerogel by volume can achieve a thermal conductivity \30 mW/m 9 K. Interestingly, a surfactant addition of 0.1 % by wt% of the water in the mixtures provides better material properties compared to a surfactant wt% addition of 5 %. However, it has been found around 40 % entrained air, affecting the material properties by reducing the binder and aerogel volume fractions within the composites. Moreover, gypsum crystallization starts to be inhibited at aerogel volume fractions [35 %. Towards material optimization, a model for the calculation of thermal conductivity of composites and an equation for the compressive strength are proposed.

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The approach of energy audits usually disregards the study of water as it considers that the supply does not involve energy consumption within the building. This paper aims to make visible both the energy footprint involved in ensuring safe water for human consumption and the collection and treatment of waste water. Furthermore, a methodology for conducting an energy audit is shown for the study of water consumption and applies it to a school to verify whether the measures proposed to reduce the consumption of water and the energy associated to it are viable. A school is chosen for three reasons. It is medium sized so the results can be extrapolated to other buildings. It presents a relevant water consumption due to the number of users, but without it being as high as a swimming pool might be. Finally it does not have a water heating system (there are no showers in the gym) so it only studies the energy consumption associated with drinking water without incorporating the effects of energy consumption for water heating.Key words: Water, energy audit, energy efficiency, sustainability, school. ResumenEl planteamiento de las auditorías energéticas al uso habitualmente prescinde del estudio del agua al considerar que dicho suministro no conlleva un consumo de energía dentro del edificio. El presente trabajo pretende visibilizar la huella energética que supone disponer de agua apta para el consumo humano así como la recogida y tratamiento de las aguas una vez han sido usadas. Adicionalmente se muestra una metodología para la realización de la auditoría energética en cuanto al estudio del consumo de agua se refiere y se aplica a un centro docente para verificar si las medidas que se proponen para reducir el consumo de agua y de energía asociado al mismo son viables. Se escoge un centro docente para el estudio por tres motivos: tiene un tamaño medio por lo que sus resultados son extrapolables a otros edificios; presenta un consumo de agua significativo debido al número de usuarios, pero sin resultar tan elevado como pudiera ser una piscina; finalmente, no dispone de instalación de calentamiento de agua (no hay duchas en el polideportivo) por lo que se puede estudiar exclusivamente el consumo de energía asociado al consumo de agua sin incorporar los efectos del consumo energético para calentar el agua.

Windows are elements of great incidence on building consumption and therefore with great saving potential. When designing high-energy efficiency windows, it is possible to negatively influence the indoor environment quality. To ensure indoor environmental quality, hygrothermal comfort, acoustic comfort, luminous comfort, physical-chemical and microbiological contaminants in the air, and the electromagnetic environment must be considered.  Of all these aspects, windows intervene in four of them:  hygrothermal comfort, luminous comfort, acoustic comfort and air quality. In order to carry out a comprehensive design, designers should study in detail the variables mentioned for each particular case and, consequently, act. This, due to the means and the deadlines with which the prescriber usually counts on, is currently not viable. This research responds to current deficiencies by proposing the development of a product indicator through an integrative procedure for window design that simultaneously contemplates indoor environmental quality, energy efficiency and cost, integrating environmental and socio-economic aspects. The indicator proposed here provides information substantially superior to that currently available to technicians, to be used as a decision making tool.

Sustainability in architecture is one of the major challenges of the twenty-first century. In biomimetic architecture, nature is the model of choice in the quest for sustainability; because it shows us the most environmentally friendly and sustainable models developed over 3.8 billion years of evolution. Antonio Gaudí said that: "The architect of the future will build imitating nature, for it is the most rational, long-lasting, and economical of all methods". Gaudí, taking nature as his model, optimises his buildings bioclimatically; he widely uses bricks and tiles-the cheapest materials at the time-, he uses local stone, and he takes advantage of waste materials or debris, and optimises the structural design of his buildings. Methodology To assess Gaudís' contributions to sustainability in architecture today, his most significant works have been studied, and bibliographical records have been made of the systems developed by Gaudí to enhance the performance of his buildings in the three fields of sustainability: environmental, economic, and social. Conclusions Gaudí was a great forerunner of sustainability and biomimicry in architecture, and teaches us that buildings conceived as "machines for living"-by the great architect Le Corbusier-can evolve and become "ecosystems in which to live". Originality Gaudís' great artistic and creative talent has been assessed together with his innovative architectural style and his technical and structural innovations; however, his role as a forerunner of sustainability in architecture has not been studied.

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An energy audit is a useful tool that sets out possibilities for improvement, optimization and energy saving. For the study of the thermal envelope, it is useful to use energy simulation tools that use suitably validated reference climates and simulation procedures. The results of the Unified Lider Calener Tool (HULC), and its subsequent processing of results, allow intervention priorities to be established aimed at aiding the energy manager of the building when proposing energy reform measures involving a degree of economic savings, so that the proposed investments allow a reasonable payback period. A teaching center has been chosen as a case study because presenting a tool that allows to save on energy consumption and quantify the payback terms of the investments is relevant. This paper quantifies the payback periods of the investments to be made to improve the thermal envelope of the building. To this end, the case study building was modeled and an economic analysis was carried out, which led to the conclusion that the most beneficial action is the replacement of the windows.

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