RFP Magazine

Passive design and low-impact construction is on the rise, reports Deborah Erwin.

The heyday of prodigal building has passed. Well, at least for those regions injured by the economic downturn. There are still the Dubais and Macaus of the world, not to mention China’s multitude of overnight upstarts, which insist on creating fantastical urban landscapes with little budgetary restraint or care for environmental impacts, but, green and resource-efficient structures are on the rise and are gaining industry momentum as a research subject and branch of practice.

Technology has done wonders for this industry, providing us with intelligent ways to go green such as smart grids, integrated building management systems, low-energy media facades, lighting control systems, and renewable energy systems. However, one need not equate high-tech with environment-friendly. There are countless low-tech means of building, many of which have experienced resurgences since their earlier days of mainstream use. In addition to restoring and reusing existing buildings, designers are also reverting to passive techniques that have once been dismissed as primitive and outmoded and exploring non-technological solutions such as pre-fabrication and modular design.

Back in the earliest days of building, local materials found on site or nearby were employed for building structures of all types, from stables to palaces. Earth, straw, clay, stone, bamboo and timber were construction staples depending on the location and its natural supply of each resource. In addition to using natural materials, our predecessors also employed them more efficiently. Today, it is both financially and environmentally vital that we minimise waste, and retain or salvage existing materials.

Passive Design
Simply put, passive design entails the application of any low-tech measure that optimises light, minimises energy, controls heat gain and maximises airflow. Painting ceilings white and cladding exterior walls with louvers are a few basic yet effective ways for controlling daylight, reducing electrical light, preventing glare and managing solar heat. One good example is Madrid’s Carabanchel social housing complex. Its entire exterior is clad with bamboo. From without, the façade appears as a unified surface but it actually comprises rows of folding doors, each manually operable by tenants. When opened, the doors reveal corridors on each floor, which double as common balconies. By installing simple, light-weight louvers inhabitants can manage their indoor environments. When sunlight is too intense, doors may be closed to keep interiors cool; and when units are too dark, the doors may be opened for natural light.

Pearl Academy of Fashion
Jaipur’s extreme and changable climate, with temperatures as high as 47 degrees during the humid Summer and as low as 5 in Winter, posed a major challenge for Morphogenesis when it was hired to design the Pearl Academy of Fashion. A limited construction budget of US$25 per sqf also meant that a creative approach was needed. Passively designed to minimise costs, materials and energy requirements, the building reasserts many Rajasthani techniques especially beneficial for Jaipur’s conditions. The ‘jaali’, a stone screen, and the use of courtyards are two borrowed concepts. Cladding the exterior, are screens constructed of local concrete which not only serve as a brise-soleil (a fixed shading devise) but also as a rainwater catchment. Projected four feet from compartments, the screen keeps the site cool and supplies water for the building’s lavatories. While integral to the academy’s passive design, this feature also endows the institution with a dynamic and engaging façade.

At the building’s base is a trough which runs along the perimeter to facilitate air flow throughout the site. The academy itself is raised above ground and features a pool in its central void to provide evaporative cooling. Stairwells and courtyards are configured for optimal ventilation and natural light, endowing common areas with shade.

As a result of this passive approach, interiors are typically 20 degrees cooler than external temperatures. Also, no mechanical systems are needed for HVAC functions and local labourers maintain the premises. Since its completion in 2008, the building’s design and strategies have been replicated by other firms in the locale, inspiring other cost-effective, environment-sensitive and attractive buildings suited for the region.

Corporate Realm
Passive architecture has huge potential across many sectors, in particular the corporate sector. “The main energy consumption in corporate comes from lighting and air conditioning,” says Manit Rastogi, Managing Director of Morphogenesis. While little can be done to minimise the electrical consumption of internal equipment – computers, servers and photocopiers – lots can be done to harvest sunlight. “When you allow for a corporate office to be fully daylit, you need to be careful of the glare. If the glare falls on the computer screen, the first thing the person is going to do is draw the blinds. The moment he draws the blind, the lights come on. The positioning of the workstations is crucial. And don’t install blinds.”

Glazing also needs to be critically selected for orientation and exposure to sunlight. For even diffusion of daylight, light shelves can be employed. “You bounce daylight off shelves with the glazing system, onto the ceiling and back into the interiors. One office we designed has been in operation for nine years and has never switched on a light. It’s very simple to do. The mistake most people make when trying to introduce daylighting is not controlling glare,” explains Rastogi. As for air-conditioning, he admits that it’s nearly impossible to convince corporates to naturally ventilate their workspaces. “So we can’t take air-conditioning out but we can reduce it dramatically, which again relies on various strategies: orientation, thermal banking – using terrace gardens, courtyards, using free-cooling at night. When the building isn’t occupied and [the] temperature is lower at night, you shut the AC off and suck in cold air from the outside, and flush the heat out of the building”.

Prefab or Modular Design
Prefabricated (Prefab) or modular construction involves the production of a building’s constituent parts in a factory, and their assembly on site. This process ensures less material wastage, less disruption to the site and neighbouring parcels, and often faster project delivery. In essence, the factory that manufactures building elements acts like a wholesaler or warehouse equipped with the relevant tools and stocked with all the required materials. Product scraps are easily collected and recycled for future projects. Fewer onsite hours also means less reliance on fair weather and less onsite cleanup. Modular construction also enables flexible reconfiguration during a building’s lifecycle, so the property may be adapted for future use.

This “use of prefabrication to optimise sustainability” is also termed “Green modular” by James Garrison of Garrison Architects. “Factory fabrication allows the execution of high performance construction detailing – including insulation and vapour retarder continuity as well as efficient structural framing practices,” adds Garrison. “Project organisation and coordination is much more labour efficient than in the field.”

He references the Syracuse University School of Architecture as an example of passive design, “the only elements that use mechanical systems are the existing interior spaces that could not benefit from passive air movement. Passive solutions must be designed with the form concept of the building. That allows a level of integration and expression that is much more complete than active system buildings. The other wonderful thing about the use of solar energy and air movement is that it results in buildings that are porous, light filled, and conducive to human interaction”. As a result, the school benefits from “a 50 percent reduction in overall energy costs as well as dramatically improved air quality”.

In Amsterdam, Allard Architecture is realising Matchbox, a small-scale mixed-use project, comprising 22
office units, a rooftop restaurant and terrace. Made of prefabricated concrete, the scheme will appear like two groups of stacked boxes – a six-storey and seven-storey block – connected by a corridor spine. Each rectangular unit sits askew from adjoining compartments to create a dynamic form and provide shading. This method of installing a building is inherently eco-friendly, says Jurrien Boon, Project Architect at Allard Architecture. Its five-metre cantilevers are to prevent the façade from overheating. “‘Dry-building-methods’ is in our opinion good because we avoid ‘gluing’ materials, so you could even dismount the whole building after a certain number of years,” he adds.

Down to Earth
One of the most abundant and popular building materials on the low-tech roster today is earth. Although it was a verifiable mainstay for builders of pre-modern civilisations, it has only been resurrected in the last twenty years as a dependable material for contemporary architecture. Rammed earth walls, one of the most common and versatile terra products, are formed by compressing soil composite which is sourced below topsoil and set with six to ten percent of cement.

In the early 1990s, Meror Krayenhoff, an environmental builder from British Columbia, Canada patented SIREWALLs (Stabilised Insulated Rammed Earth walls). This product mixes inorganic soil with a small amount of cement to form a wall, then reinforced with steel rebars. From an environmental perspective, rammed earth walls use significantly less cement than concrete which requires 20 to 30 percent cement. Foundation work is also less disruptive to the site. Although initially more costly than concrete walls, rammed earth walls do not require siding, vapour barriers, sheathing, interior insulation, drywall, paint, or trim.

Earthships
Another earth-obsessed entrepreneur, Michael Reynolds of Earthship Biotecture, employs terra, tires, clay and glass bottles to make houses. Depending on the size of the building, between 500 and 5,000 recycled automobile tires are packed with earth and stacked much like bricks to form walls. Since its main walls are load bearing, no concrete foundation is needed. Earthen plaster made up of dirt, sand, clay, straw and water coats the poche. The earth and tire walls have thermal mass which naturally heats and cools interiors, retaining solar heat during the day and releasing it at night (or when temperatures drop). Interior walls also reuse materials, particularly aluminium or steel cans; or glass bottles.

Built for self-sufficiency and sustainability, these buildings are equipped with solar panels which charge a bank of batteries for energy distribution throughout the house. Water catchment systems and cisterns also supply the building. Since self-powering, these houses do not need to be connected to any energy grids. Presently, “earthship colonies” are taking root in Brighton, UK, and in New Mexico, US.