LLUM

Located in Curitiba, southern Brazil, Llum is a 20-story multifamily residential project with 15 “suspended homes,” designed to provide families with the comforts of a single family residence and the convenience of an apartment building.

Laguna, its developer and builder, has always seen LEED as an outcome, not as a goal. According to Gabriel Raad, the company’s CEO, “if you build a really comfortable, excellent building, then one of the natural outcomes is LEED.”

Even though LEED certification was not part of the initial design brief, the project did have a very clearly defined set of goals in terms of occupant comfort, energy efficiency and sustainability. As such, for just 1% in additional cost to the project—covering all the costs associated with design and construction, including investment in an on-site renewable energy system—the project achieved LEED Gold in January 2020.

Curitiba has a mild subtropical high-altitude climate, and homeowners prefer operable windows for thermal comfort control, even in larger apartments like the ones developed by Laguna.

A key aspect of Llum’s design is the principle that a more comfortable building is also a more energy-efficient one. Laguna set a design goal that the building should provide adequate thermal comfort to eliminate the need for mechanical cooling and heating 90% of the time. The building façade plays a critical role in preventing excessive heat gain in the summer and capturing the sun’s warmth in the winter. Llum has a glass façade, which might make you imagine a glass box-style home, but the window-to-wall ratio is just 25%, with window openings carefully considered by exposure—north: 64%; west: 23%; east: 11%; and south: 2%.

Alongside operable windows, Llum was designed with a direct outdoor air system (DOAS), to ensure that all spaces are supplied with fresh air during all times. As a result, meeting LEED’s requirements posed no barriers to the project.

Llum means "light" in Catalan, and light was the inspiration for this building. Not only does the glass façade provide thermal comfort, but it also allows the residents to enjoy plenty of natural daylight.

The buildings’ design incorporates a number of biophilic design elements which include a stunning entrance staircase, a spiral that curls up and assumes the organic shape of a nautilus shell. The interior design of common areas uses natural materials, such as wood, stone, wool and cotton, and a color palette of soft earthy tones, to create a cozy, relaxing environment. The play area for children, a sundeck and landscaped outdoor terrace—accessible to all building occupants—are planted with Jaboticaba berry trees, a native Brazilian species.

Llum is just the latest in a long line of projects where occupant comfort and well-being drove the design, helping to redefine what a “market building” can be in Brazil. It is evidence that it’s possible to develop vastly more efficient, comfortable and sustainable residential buildings and still be competitive.