The most recent project as part of the Mexican Papalote Children's Museums is the Papalote Verde Museum for Children located in Monterrey in Fundidora Park, a former steel mill in the northeast of the country. The area is the size of approximately 9038 m² (97284 ft²) and is partially built underground. The Papalote Verde strives to be different from traditional museums, with a unique structure and a multitude of spaces. Architecture and museography are intertwined and share the common goal to allow every visitor his or her own tour without interfering with the learning process. An essential message the museum wants to convey to its visitors - and the reason for its name, Papalote Verde or "green butterfly" - is the need for people to take responsibility for their actions and become aware of the influence humans have on their environment. The invitation to touch, learn, and play is extended to visitors throughout the five thematic areas with 80 interactive offerings. Consequently, sustainability is essential. Realizing this key point, Transsolar developed the climate concepts for the rooms with help of CFD simulations and developed the daylight supply in compliance with the targeted standards. An existing building was well insulated for reuse. A large part of the new building is located underground; it still gets plenty of natural light for lighting, but solar heat gains remain low. The building envelope design is as airtight as possible to keep out infiltration during the hot and humid season. In spring, natural ventilation is possible. Wastewater is reused on site. Photovoltaic panels on the roofs generate electricity. Environmentally friendly materials shall be used; the overall carbon footprint should become as low as possible. Energy efficiency was successfully implemented in the design: The building was planned to achieve the LEED platinum certificate (Leadership in Energy and Environmental Design) and thus the best classification for an ecological building in the rating system developed by the US Green Building Council. Only a project that combines sustainable constructions with low use of resources while using renewable energies is able to achieve this certification. It could become be the first building in Mexico to receive this prestigious award and proves that Papalote Verde unites and promotes sustainability through concept and design.