How Having a Green Roof Can Reduce the Effect of Heat Islands
Changes in temperatures can be driven by the development of roads, infrastructure, and large buildings in a small area. Did you know that a “heat island” can be formed by replacing natural vegetation with concrete and urban structures, making a metropolitan area warmer than its surrounding areas? These elevated temperatures during warmer seasons create an increased demand for cooling solutions directly affecting your energy bill.
How a Heat Island Affects Your Energy Bill
Cooling demand in cities is high during the heat island’s hottest seasons. To beat the island heat, engineers developed green roofs to reduce cooling costs in homes and offices. Green roofs have been popular for decades, mainly in European cities and are now becoming more common in the US.
There are two types of green roofs:
Extensive Green Roof
Extensive green roofs feature a thin substrate layer and moss layer vegetation. Known mostly as 'eco-roofs' they are generally chosen for their low maintenance and ability to be self-sustaining. Hundreds of plants can be grown with little maintenance and the vegetation replaces tiles and other conventional roof coverings. Herbs and grasses can be a supplement with a non-permanent irrigation system. Swarthmore College’s David Kemp Hall and the Bronx County Courthouse are great examples of extensive green roofs.
Intensive Green Roof
Intensive green roofs feature advanced irrigation systems that require professional maintenance. The roof is characterized by different vegetation from small trees to herbaceous plants, they offer more options for plants providing greater landscape design potential and increased biodiversity. Cruise ships, Chicago’s City Hall and Chicago’s Peggy Notebaert Nature Museum, are good examples of intensive green roofs.
The Green Roof Advantage
Some advantages of having green roofs are:
- This roof works as a super insulator by reducing cooling expenses inside the building.
- The building can hold in more heat in winter and keep out the heat in summer.
- Reduction of noise pollution as the plants and soil combine to absorb and prevent outside noise.
- Aesthetic value through landscape design, providing shade and food for insects and birds.
- Durability as the plants and soil mixture guards the waterproof membrane against high heat and direct sunlight.
- More oxygen and less carbon monoxide emitted in the air. The vegetation collects carbon monoxide and refills the atmosphere with oxygen helping to reduce carbon emissions.
Green Roof Installation Costs and Maintenance
The EPA approximate installation charges are $10 per square foot for the extensive roof. An intensive roof is approximately $25 per square foot. Yearly maintenance charges for either roof per square foot can range between 75 cents to $1.50 based on the types of plants chosen and the amount of irrigation, fertilization and maintenance required.
EPA Study on the Environmental Effect of Green Roofs
The EPA study shows green roofs mitigate the heat island effect, reduces air pollution and greenhouse gas emissions, and helps reduce energy costs. Methodologies are laid out using free tools created by EPA to assess the many benefits of green roofs. Regulatory mandates and voluntary incentives are ways cities pursue green roof implementation, and a long list of cities and communities have already adopted them.
Beat the island heat with a green roof. Contact us for more details on sustainability.
Architect Jean Novel is Presented with the Visionary Urban Integration Award for the Design of 53W53
One of the most adventurous additions to the New York City skyline is the innovative design of 53W53 by Pritzker Prize winner Architect Jean Nouvel. At a height of 1,050 feet and developed in step with the Museum of Modern Art’s 65,000 sq. ft. expansion, New York City now has a new, bold yet graceful exclamation point.
53W53 is a super slender tapered form that slopes at two distinct angles with exposed structural elements arranged in an asymmetric pattern and sheathed in a taut glass skin. This unconventional lattice, anchored and connected by diagrids – a custom designed set of steel boxes and plates, was envisioned and executed by the structural engineer WSP / Parsons Brinckerhoff. The structural solution smoothly merges with the architectural intent providing a single, exterior structural system matching the geometry of the diagrid and having the ability to carry both vertical loads and those associated with wind and seismic loads.
Adverse geotechnical composition of the site and the proximity of MTA tunnels presented an interesting engineering challenge. More than thirty reinforced concrete caisson were required, some reaching depts of 70 feet deep.
Another challenge involved locating major equipment at the apex, including a cooling tower, 500 ton tuned mass damper, elevator machine room, fans, pumps and window washing rig, all within the building’s most narrow portion.
There are 5,747 triple-glazed curtain-wall panels of various shapes and sizes with a sleek black high-performance coating to both minimize exterior noise and maximize thermal comfort. Grey metal panels applied to the exterior of the curtain-wall trace the structural elements behind, expressing Nouvel’s signature design.
The attenuating form and exposed structure gives each home inside a different shape and layout, while the intricate structural pattern frames views of the surrounding city.
"Architecture is art, and architecture is born from its situation, from its context," says Nouvel. The Architect’s vision; the dense, verticality of Midtown Manhattan; and the complexities of site, structure and envelope are the context for this visionary architecture.
Ateliers Jean Nouvel and WSP were recently presented with the Visionary Urban Integration Award by the New York Chapter of the Society of American Registered Architects.Read more...