The Casa dels Xuklis is a sustainable accommodation for children with cancer designed by MBM Arquitectes (Josep Martorell, Oriol Bohigas, David Mackay, Oriol Capdevila and Francesc Gual). This project, driven by AFANOC and the Private Foundation of Children with Cancer, is located in Barcelona and will receive its first residents in October 2011. The project has taken 5 years to be a reality, and was promoted by AFANOC. This organization detected that there are families with children diagnosed with cancer who live too far away from the hospital, and have difficulty in finding adequate accommodation for the frequent visits that the various treatments require. At the same time, an optimal environment contributes in affected children caring. The Casa dels Xuklis presents a holistic response to sustainability that covers natural resources as well as social and technical design aspect of the building and garden. The Casa dels Xuklis responds a new demand of health buildings. The building architecture responds to the climate and culture of the Mediterranean: natural light, cross ventilation, in dialogue with the sun, the patio and the garden and in reference to the four seasons. The building has two main parts: the apartments (where families live) and the public areas. The twenty-five 30 m² apartments are grouped in four separate pavilions each facing a different way around the traditional Mediterranean patio tilted in plan to create social corners. Each dwelling has a covered porch facing the garden, protected with two slatted wooden doors, that when opened extend the privacy into the garden itself. This ensures a delicate balance between privacy and community relationships while the patio, with its cubic basin with the splash of recycled water from the fountain, together with deciduous tree creates an agreeable micro-climate for the families together. The more public accommodation, the library with its different areas for small groups, the dining area with the porch giving protection from the mid-afternoon sun, and the community kitchen in the centre are gathered together under a separate roof that follows the irregular curves of the plan. Over the kitchen there is an attic overlooking the library for conferences and other future activities. In the construction care has been taken to ensure a continuous thermal insulation with a cavity walls and roof wrapped around the building. Sound insulation between dwellings is reinforced with acoustic prefabricated plaster panels on either side of the structural walls, and beneath the zinc roof to mitigate excessive noise from the rain. Led lighting has been installed in the public areas as far as the restricted budget allowed. Throughout the landscape of the garden a special design of the drainage system is integrated with the recycling of the watering of the trees and plants. Finally, a kitchen-garden provides vegetables, grown on site, for the families, not only for meals but also for its natural therapeutic effect of distraction.