Letting Nature Do the Work: Elm Park’s buildings use natural ventilation and daylighting to radically reduce energy use even as they reinvent the suburbs with new ideas about density
Driving south at the edge of Dublin, one finds Dublin Bay on one side, mountains on the other, and suburban sprawl in between. It’s not the first place one would look for a high-density, mixed-use development, but that is precisely where Radora Developments located Elm Park. The 15-acre site, nestled between a convent and a suburban housing development, has a density about six times that of the surrounding area and includes offices, a healthcare center, market-rate and afford-able housing, a daycare center, a conference center, a restaurant, and a fitness center.
Based on what you have seen and read about this project, how would you grade it? Use the stars below to indicate your assessment, five stars being the highest rating.
In many places, such a development would face stiff opposition from the surrounding neighborhoods, but architect Merrit Bucholz of Bucholz McEvoy Architects says that there were “no serious objections despite the fact that the site boundary is suburbia.” Elm Park is provid-ing a new model for development in Dublin, which Bucholz calls “a sprawling city.” The European Environment Agency called Dublin a “worst-case scenario” of urban planning in a 2006 report, citing housing sprawl and reactionary policies stemming from failed high-rise tenements as reasons for the city’s planning problems.
Density isn’t the only aspect of Elm Park that sets it apart; innovative environmental features place it among the more advanced green developments in Europe. The buildings merge form and function, making beautiful use of the site’s microclimate for ventilation. In Dublin, according to Bucholz, prevailing winds drive design more than sunlight. As a result, the long, narrow buildings are oriented on a north-south axis to take advantage of those westerly winds.
In the three office buildings, openness on each floor allows cross-ventilation. Wind blowing over vents on the top of the buildings pulls air in through openings on the east facades, over to thin atriums on the west facades, where it moves up and out of the buildings. These same atriums create thermal chimneys to maintain cross-ventilation on the few sunny, windless days each year. Incoming air flows over hot-water pipes located near the east facades, fed by the project’s combined heat-and-power plant, to heat the building in cold weather, but with Dublin’s moderate climate, not much is needed. The residential buildings also make use of cross-ventilation, with each apartment occupying the entire width of the building. A similar system works in the medical center and hotel. Because these buildings have individual rooms instead of open-floor plans, ventilation air moves from exterior windows to thermal chimneys in the middle of the building.
Although the ventilation scheme dominated the design and orientation of the building, the project team did not ignore the sun. Dublin is often cloudy, so, says Bucholz, “We modeled the buildings in various orientations in low-light or overcast conditions and found this minimized any effect of overshadowing by not preferring either an east or west orientation.” Vertical sunshades, the tall and narrow atriums on the west facades, and other design features on the buildings limit glare from strong morning and afternoon sun. In the office buildings, cast-concrete ceilings slope up from the center of the floorplates to the exterior walls over the open floors, bringing sunlight deep inside. The residential buildings are designed with the bedrooms on the east to get morning sun while living areas get afternoon light. Glazed balconies offer warm sunny spaces in the living quarters in the winter and open to provide cross-ventilation in warmer weather.
Natural ventilation strategies are often considered risky by real estate agents, who argue that clients will be concerned about occupant comfort. But so far, the development is proving desirable.
Of the three office buildings, one is occupied by Allianz Insurance, and the other two are rapidly filling with tenants. The condominiums are largely sold; other than the hotel, the rest of the development, including senior housing, clinic, and daycare, is occupied by government entities.
Balancing comfort with energy performance requires education and occupant commitment. Bucholz notes, “We work very closely with the users to ensure that the energy outcomes are achieved and that occupants develop a sense of ownership of the building.” The architects have met with the tenants of the office buildings about their work patterns and how the building works. These meetings helped staff tune the building management system to meet the needs of the occupants and maximize energy efficiency. According to Bucholz, the approach has worked: Six months into a year-long commissioning process, the buildings are performing well.
The design of Elm Park brought together many strategies that Bucholz McEvoy had been working with over time, but that did not make the design and construction process straightforward. “Industries are set up to run and deliver projects in certain ways,” Bucholz says, and “the suspension of some of these ways of doing things and the adoption of new techniques and technologies was a seriously complex undertaking for us as architects.” The firm studied energy use, daylighting, and structural performance. And they investigated how individual building components could be built and installed.
Much of the construction involved installing prefabricated components. The curtainwall facades and the large glue-laminated timber structures that support them were built in a factory and lifted into place. Full-scale mockups in the factory before construction allowed the team to study the structural stresses on the support members and adjust the design. Much of the inner concrete structure of the buildings was also prefabricated, particularly the sloped ceiling wells, which were modeled to scale to study their performance, then cast in custom molds.
A development the size of Elm Park requires significant parking. Although the project is connected to the city center by public transportation, many occupants and visitors drive to the development from the surrounding suburbs. To minimize the impact on the site, the project team moved the parking underground to free up space for lawns and pavilions. Large wells open up the underground structure, bringing daylight and ventilation to the space and providing entrances to various buildings. Concrete supports rise out of these wells, drawing the eye up and joining the parking area to the buildings visually.
On top of this structure, seven acres of green space tie the site and its buildings together. Far from flat, constructed slopes provide visual interest and drainage, directing runoff to large pine, maple, oak, walnut, birch, and ash trees. Stretches of grass are broken up by large shrubs and native grasses, as well as rain shelters that mimic the large supports on the buildings. Bucholz calls the landscape a “giant sponge” that absorbs rainwater, keeping it from entering an overburdened stream that collects runoff from a bordering golf course.
Elm Park shows that naturally ventilated and lit buildings do not have to be a hard sell, and that dense development in the suburbs is not necessarily an oxymoron. Dublin is not unique in its moderate climate that makes the ventilation and daylighting strategies work. Although other municipalities may offer more resistance to dense development, Elm Park proves that such projects are possible and even desirable, drawing jobs and commerce into depressed or undeveloped areas.
share: more »