Today’s architects and building designers are more and more concerned with the relationship between architecture and the environment in which it is ‘housed’, thus also concerning themselves with the thermal comfort of internal spaces, utilising design plans for natural climate control.
Therefore, the design process now integrates more strategies known as passive systems, tools used to moderate temperature, to attain harmony linking the natural and the built environment, considering the needs of every space, like localised micro-climate and its natural resources.
Although these systems may differ greatly according to locale, a few essential principles should be adhered to guarantee the mastery of passive systems. Aside from the natural ventilation and lighting, passive measures also include the use of the fitting materials that enhance thermal mass, and specific design elements, such as indoor greenery and reflecting pools.
Certain residential projects illustrate their application.
Natural ventilation is a popular passive design solution that shifts fresh air through the internal spaces due to air pressure variations. In cross ventilation, for instance, by positioning the openings on alternate sides of the room, the pressure differential encourages airflow, as in the Lee House, designed by Marcio Kogan and Eduardo Glycerio, in which large sliding doors lower the temperature of the main living area, or in the FVB House with its red wooden lattices, circulating air to circulate throughout the residence.
Also in regards to ventilation, one can also apply the stack effect in which warmer and denser air rises and the cool air falls. Double-height ceilings compliment this air exchange, as witnessed in the Sloth’s House in Guarujá, São Paulo, which offers a mixture of optimum lighting, cross-ventilation, and needs no air conditioning.
Also, interior courtyards help to promote the passive cooling of buildings, like the Infiltrated Patio House, constructed in the hot atmosphere of Mérida, Mexico, or the House of Silence and the House Among Trees in Ecuador, one offering a partly concealed courtyard with little vegetation, the other an open courtyard with substantial greenery.
In the arena of natural lighting, another key element is shading. A good sunscreen should limit solar gain in the hot seasons without blocking it totally in cooler months or stopping entry of natural daylight. Many design elements can be used for this purpose, including the method known as the brise-soleil, utilised in the Boipeba House, carved wooden slats, or in the Soul Garden House, via metal perforated panels.
Building materials are essential in ensuring thermal comfort by way of passive strategies. For structures based in extremely hot climates, certain materials can boost the home’s “transpiration” and serve as thermal barrier that stop solar gains. Buildings in cooler climates can enhance thermal inertia by maintaining heat and releasing it at night. Certain materials with elevated thermal capacity include concrete, brick, solid clay, and stone, as discovered at the Half Buried House, which employs soil to establish appropriate thermal inertia for the regional climate, and the Family House in La Pereda, both in Spain.
Water ranks among the most aged and most energy-efficient methods of passively cooling a structure, particularly in dry climates. Evaporative cooling removes heat from the environment or material by way of water evaporation—as is found in the Nivaldo Borges Residence, by Lelé, another signature masterwork of Brazilian architecture, where gardens and a reflecting pool border the deluxe living area and study room, and the Bacopari House, by UNA Arquitetos, in São Paulo.
And, of course, when it comes to building tools, vegetation is as green as it gets. Inside and outside, it cuts back on solar radiation and forms a microclimate that guarantees improved thermal comfort conditions. Vegetation-centred designs include the MM Tropical House, built in tropical Southeast Asia, and employs vegetation as a tool to make solar gain minimal.
Certain projects offer vegetation on the roof, which supplies great thermal comfort inside the building, thus lessening energy consumption for heating or cooling purposes. The LLP House in Spain, for example, is a Passive House featuring a roof garden, a compact built environment, solar capturing and protection, thermal resistance, and cross ventilation.
Perhaps the best building materials needed to achieve optimum thermal comfort through passive design are design knowledge and architectural creativity—the two qualities that always inspire the best built solutions.