Revirando a Teoria: Eco House URCA

In the Urca neighborhood near the base of Rio de Janeiro’s Sugarloaf mountain, architect Alexandra Lichtenberg tackled a remodeling project that demonstrates that being green isn't the exclusive domain of high-cost, luxury residences and backwoods off-grid dwellings. A good green remodel is within reach of the average well-intentioned homeowner in the average urban neighborhood anywhere in the world, and the EcoHouse proves it.

before the project

after the project

Green roofs and facades

Green roofs enhance passive cooling capacities, absorb rainwater, and offer another usable outdoor space for residents—a perfect spot for cultivating a garden. The EcoHouse's old ceramic tile roof was replaced by green roofs, using mostly grass and cooking herbs. All northwest-facing façades were fitted with an aluminum trellis to protect the outside walls from sun exposure. A vigorous vine will climb the trellis and create a shield to absorb most of the direct radiation that would hit the walls.

Sewage recycling

Even the most hardcore environmentalists sometimes shy away from dealing with gray water and sewage. However, there are a number of well-designed compact sewage treatment systems that make residential water reuse easy and clean. A Brazilian company called Mizumo provided a test system for the Ecohouse Urca Project. Intended for small urban lots, it measures 1.20m x 2.60m x 2.10m. The system is meant to provide water for the same non-potable uses as the rainwater system. Before being pumped to the water tank on the green roof, the water undergoes sand and UV light filtration to eliminate any remaining impurities.

Sistema de captação e fluxo de água

Natural ventilation

Natural ventilation is another component that is often best installed during the initial building process of the home, when operable skylights and windows can be designed into the building. For the EcoHouse remodel, the architect did a reconfiguration of the internal layout to allow for natural ventilation. Air circulation is vitally important, not only to reduce heating and cooling costs, but for the health of the inhabitants. Keeping a good inflow of fresh air enhances the interior atmosphere so that it never feels stuffy or stagnant.

Ventilação nas paredes com jardins verticais

Renewable energy

Two solar systems heat all the hot water in the house, both working in a passive thermosiphon system, which takes advantage of gravity and eliminates the need to pump liquids around the house. Normally, solar panels mounted on the roof heat water in a tank several floors below, which means that the liquid needs to be pumped to the roof for heating. In a thermosiphon system, the tank is on the roof, placed above the solar collector.

As the temperature of the heat-transfer fluid increases, its density decreases. The fluid rises, causing natural convection, which permits passive circulation in the pipes. In the EcoHouse, one of the two solar systems has an electrical backup source. The other functions completely on solar.

Passive Cooling

The best means of achieving passive heating and cooling is through well-planned orientation of a house on its site. With existing buildings, though, there are other ways to make use of passive technologies, such as strategic placement of shade trees, extension of eaves and overhanging roofing, and window glazing. Keeping the walls, windows and roof of the house cool by deflecting or avoiding direct sunlight, the inside stays cooler, as well, without A/C or other high-energy systems.