Green Roofs—How to Add This Value-Enhancing Amenity in Multifamily Housing
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This document discusses green roofs, which are vegetative systems installed on top of buildings. It describes the components of green roofs and provides a brief history. It then outlines the numerous benefits of green roofs, including financial benefits from increased roof lifespan and reduced energy costs, environmental benefits such as decreased stormwater runoff and reduced urban heat island effect, and social benefits like increased biodiversity and outdoor space. The document also reviews challenges of green roofs and cities with large amounts of green roof space. It examines incentives and regulations to promote green roofs in various cities through tax incentives, grants, fee reductions, zoning bonuses, and green building standards. Finally, it differentiates between extensive, semi-intensive and intensive green
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Green Roofs—How to Add This Value-Enhancing Amenity in Multifamily Housing
- 2. What are Green Roofs? A green roof is a vegetative system or other green/garden space on top of a building or other structures, from single-story buildings, parking garage roofs to high-rises, often many stories above the ground. Most green roof systems include: • water proofing system • root barrier • drainage system • filter cloth • a lightweight growing medium and • various/appropriate low- maintenance, drought-resistant plants
- 3. Green Roofs – A Brief History • First green roofs were ziggurats dating back to about 3000 b.c. • Hanging Gardens of Babylon, built by King Nebuchadezzar II around 500 b.c. to console his wife, Amytis, who longed for the native landscape of her homeland, Media • Romans planted trees on roofs • Sod roofs of Iceland/Scandinavia • Modern green roof technology began in Germany in 1960s. • At least 10% of all roofs in Germany are now “greened.” Image from History.com
- 4. Benefits of Green Roofs Green roofs provide numerous benefits to building owners, residents and the community: Financial Benefits • More than doubles average roof life from 17 years to more than 40 years • Lower sewer and stormwater fees from reduced water runoff, up to $14/sf on average over 50 year life of green roof (under certain conditions can offsetting cost of roof by 30% or more and even avoid sewer connection all together) • Lower energy costs (particularly for single story and floors immediately below), about $6-8/sf due to increased insulation and heat/cooling loss and cooling ambient air immediately above roof • Potential income from urban agriculture, use of amenity space • Increased marketability, sales, rental value • Higher property values 4-11% or more (even neighboring buildings)
- 5. Benefits of Green Roofs Environmental Benefits • DRAMATICALLY reduces stormwater runoff and combined sewer overflows – up to 65-90% annually. In summer, green roofs retain 70-90% of the precipitation that falls on it in their plants and soil, in winter, about 25-40%. Used in plants and then returned to atmosphere. • Improves stormwater runoff quality and reduces pollution and contamination of waterways by CSO overflows by filtering water through the system • Reduces “heat island effect” by cooling air around buildings • Improves air quality by absorbing CO2 and releasing oxygen • Increased biodiversity and natural habitat
- 6. Benefits of Green Roofs Resident and Employee Health and Well-being • Outdoor recreation and community gardening space for residents providing sense of pride, wholesome activities, healthy food production • Noise reduction: green roofs can reduce residents’ indoor sound from traffic, construction, airports, trains by up to 40 decibels • Aesthetic views and natural beauty that improves mental and emotional well-being, productivity, reduces stress
- 7. Benefits of Green Roofs Miscellaneous • Creates local jobs • Increases municipal/state tax revenue • Reduces stress on municipal infrastructure • Federal clean water act innovative best practice
- 8. Challenges • Installation cost – a long-term investment rather than an expense • Retrofitting • General installation logistics, e.g., bringing soil and equipment to roof • Maintenance access • Rooftop climate "Wind is a big challenge for us. We use a lot of cover crop to prevent erosion, particularly in winter, and cultivate taller plants like sunflowers as windblocks. But our unique environment offers its own benefits, as well as challenges. We're helping our city manage stormwater, and decreasing urban heat island effect.“ Anastasia Cole Plakias, co-founder, Brooklyn Grange.
- 9. Cities with most green roofs According to Green Roofs for Healthy Cities’ 2014 Annual Green Roof Industry Survey, the top ten North American metro areas in green roof sf installed in 2014: 1. Washington, D.C. 2. Toronto 3. Philadelphia 4. Chicago 5. New York City 6. Denver 7. Baltimore 8. Montreal 9. Seattle and 10. Boston As of 2014, about 30-40 million total sf in green roofs have been created in North America.
- 10. Incentives and Regulations Toronto is the first City in North America to pass a bylaw to require green roofs on all new construction of commercial, industrial, institutional and multifamily residential development, and all public buildings. Gives developments incentives of $7/sf. Though only city so far that outright requires, many have offered incentives • Tax Incentives • Grants and Loans • Stormwater, sewer and other fee rebates and credits • Priority and bonuses for zoning, building permits and utility hookups • Green building design Some of these “carrots,” particularly some of the grants and loans, are disappearing and becoming “sticks” through increased stormwater, green design and other requirements that make it financially attractive to install a green roof, or otherwise face higher fees.
- 11. Incentives and Regulations – Tax Abatements/Credits Many cities, states and the federal government offer tax incentives to encourage the construction of green roofs and offset a portion of their cost: Examples: • Philadelphia: 25% tax credit of total costs of green roof up to $100K (must meet minimum coverage requirements) • New York State/City: One year tax abatement of $5.23 per square foot, up to $200,000 or the building's tax liability, whichever is less (Effective through March 2018) • Federal Tax Credit: up to $1.80 sf for buildings meeting ASHRAE standards
- 12. Incentives and Regulations – Grants and Loans City, State and Federal Grants Low- or even zero-interest rate loans Examples: • Washington, D.C.: The 2015-2016 Deptof Environment green roof rebate program base funding of $10/sf, and up to $15/sf. No cap on the size of projects eligible for the rebate and properties of all sizes including residential, commercial and institutional are encouraged to apply. • Milwaukee: Reimbursement grants up to 50% of green infrastructure costs, including green roofs • New York City: Matching grant funds for design and construction of the green infrastructure system that manage 1" of stormwater runoff from the contributing impervious area. Eligible projects include blue roofs, rain gardens, green roofs, porous pavement and rainwater harvesting on private property in combined sewer areas. • Onondaga County NY: “Save the Rain” Green Improvement Fund (GIF) supports the development of green infrastructure and stormwater mitigation techniques on private property • Fannie Mae: Multifamily Green Building Certification Pricing Break program.
- 13. Incentives and Regulations – Fee Credits/Rebates MANY cities offer this credit as they raise stormwater and sewer fees to encourage stormwater management Examples: • Minneapolis: Green roofs qualify for up to 100% (depending on quantity of stormwater reduction) of stormwater utility fee • Nashville: Combined monthly sewer credit of $10 x total sf of green roof installed for up to 60 months or max. credit. Several stormwater fee reduction incentives, up to 75% of user fee, including for green roofs
- 14. Incentives and Regulations – Zoning and Permit Priorities Some cities give developers density or zoning bonuses or priority for permit applications that meet certain green requirements, including plans for green roofs. Examples: • Austin: Green roof density bonus allows developers to build an additional 8 sf of floor space for every sf of green roof installed • Chicago: Green permit program gives fast-track permitting and potential for reduction in permit fees for green elements, including green roofs • Seattle: Floor Area Ratio (FAR) bonus: Developers can build an extra 3 sf per foot of green roof without seeking additional permits
- 15. Incentives and Regulations – Green Building Ratings Many cities now require new and major rehab buildings to meet green building requirements, often Leadership in Energy and Environmental Design (LEED) or other green design certifications. Green roofs offer major points in numerous categories of green design certification applications Examples: • LEED: Various points towards certification, including: • Protecting or restoring habitat • Maximizing open space • Using alternative surfaces for roof • Water efficient landscaping • Energy performance • Material reuse • Enterprise Green Community Criteria: (adopted by many state housing finance agencies have incorporated into their Qualified Allocation Plans that give developers extra points on their LIHTC applications for meeting certain green building and operations standards) gives points for green roofs for access to pen space and stormwater reduction measures.
- 18. Extensive Green Roofs • Shallow (2.5-5 inches) growing medium • Ideal for low weight bearing roofs and high wind/low water sites • Low (relative) cost • Low maintenance/no permanent irrigation necessary • Uses drought-resistant sedums, succulents, small grasses, herbs, mosses Photo courtesy of Hanging-gardens.com
- 19. Semi-Intensive Green Roofs • Medium depth (5-8 inches), depending on roof) • Higher cost than extensive green roofs • Moderate maintenance (occasional irrigation needed depending on site/plants) • More biodiversity, but focus still native/low-water perennials, sedums, ornamental grasses, variety of herbs and edibles, small shrubs • More stormwater retention Photo courtesy of Hanging-gardens.com
- 20. Intensive Green Roofs • Full-blown roof gardens, patio decks and rooftop farms • Deep (8-24+ inches) growing medium • Strong weight-bearing roof structure necessary • Highest cost • High maintenance – similar to most gardens • Variety of vegetation and design, including lawns, trees, shrubs and bushes, raised beds, recreational green spaces, most perennials, rooftop farming. • Often includes walkways, benches, playgrounds, structures, sculpture and ponds • Potential to shorten ROI through urban agriculture sales, amenity use fees Photo courtesy of Hanging-gardens.com
- 22. Types of Green Roofs -- Comparison Extensive Semi-Intensive Intensive Cost (not incl. engineering) $8-12/sf (trays about $16/sf) $12-18+/sf $25-100+/sf Depth 2.5– 5 inches 6-12 inches 8 - 24+ inches Types of Plants/Diversity Less diversity/Drought- resistant sedums, succulents, small grasses, herbs, mosses More diversity. Native/low-water perennials, sedums, ornamental grasses, variety of herbs and edibles, small shrubs Significant biodiversity. Variety of vegetation and design, including lawns, trees, shrubs and bushes, raised beds, recreational green spaces, most perennials, rooftop farming. Maximum Weight 10-40 lbs/sf 45-95 lbs/sf 80-300+ lbs/sf (depends on roof) Maintenance Low Moderate Similar to any garden/urban farm Source: International Green Roof Association
- 32. Basics of Installing Green Roofs What You Need to Know • Existing roofs--Best time to do it when re-waterproofing roof to ensure compatibility • Don’t compromise existing roof and waterproofing warranty—check with roof manufacturer for green roof spec’s • MUST get a structural engineer to inspect, determine roof weight load and recommend type of system that roof can support • Find competent trained installers • Growing medium – NOT soil/compost! A lightweight mineral-based particulate (e.g. expanded slate, shale, clay or volcanic pumice) blended with organic matter, designed for use, type of plants to grow
- 34. The Brix, Milwaukee, Wisconsin Before and after installation Photo courtesy of Hanging-gardens.com
- 44. Blue Roof System What is it? A non-vegetated roof that temporarily stores rainfall on the roof surface, detaining it and slowing runoff into the sewer system. Blue roofs can also be used to capture and route rainfall for irrigation and other non-potable uses A blue roof captures rainfall, allows some evapotranspiration, and releases the remaining rainfall slowly, thereby reducing the runoff volumes and delaying peak flows. A blue roof system requires a secondary waterproofing membrane and uses small openings, placed inside inlets of roof drains, to capture rainwater then slowly release it. Advantages: • Less expensive than subsurface storage or green roofs • Reduces strain on the sewer system during the peak of rainfall events • Often included in local incentive programs Limitations: • Best for roofs with slopes less than 2 percent
- 45. Maintaining a Green Roof All green roofs need some maintenance. The more intensive, the more regular garden maintenance. But even extensive roofs need maintenance in early years. Training of maintenance staff and access to roof for regular maintenance is vital: • Watering and/or temporary supplemental irrigation until plants set (first year for most roofs, unless doing intensive garden-type) • Soil testing and fertilizing • Weeding and mowing • Checking for disease, fungus and pests • Inspecting drainage system • Repairing leaks and clogs
- 47. Resources § EPA, Implementing Green Roof Projects at the Local Level https://www.epa.gov/sites/production/files/2014- 07/documents/implementing_green_roof_projects_at_the_local_level-neelampatel.pdf § Green Roof Energy Calculator http://greenbuilding.pdx.edu/GR_CALC_v2/grcalc_v2.php#retain § Green Roofs for Healthy Cities http://www.greenroofs.org § GreenRoofs.com (Green roof industry resources) http://www.greenroofs.com/index.html § Hanging Gardens: http://www.hanging-gardens.com/# § International Green Roof Association: http://www.igra-world.com/index.php § THE LANDSCAPING AND LANDSCAPE DEVELOPMENT RESEARCH SOCIETY E.V. – FLL Guideline for the Planning, Execution and Upkeep of Green-Roof Sites http://www.greenroofsouth.co.uk/FLL%20Guidelines.pdf § Liveroof http://www.liveroof.com § The Benefits and Challenges of Green Roofs on Public and Commercial Buildings: A Report of the United States General Services Administration http://www.gsa.gov/portal/mediaId/158783/fileName/The_Benefits_and_Challenges_of_Green_Roofs _on_Public_and_Commercial_Buildings.action § The Monetary Value of the Soft Benefits of Green Roofs, Tomalty et al (2010) http://www.greenroofs.org/resources/Monetary_Value_of_Soft_Benefits_of_Green_Roofs.pdf
- 48. Sustainable Affordable Housing Management: A Money-Saving Guide to Keeping Your Site Green, Healthy & Energy Efficient Create and Implement Sustainability Plans for Your Site This comprehensive guide will help owners and managers of affordable housing sites create and implement sustainability plans for their sites. This guide explains how to: Ø Save money by reducing energy and water consumption; Ø Get residents to adopt “green” practices, such as recycling and composting; Ø Get incentives for sustainability initiatives, including major energy-saving improvements and retrofits; and Ø Improve the health of residents by: • Reducing their exposure to toxic paints, pesticides, cleaning products, and other chemicals • Improving their access to healthy food • Creating a community garden • Implementing a no-smoking policy Sustainability plans don’t just help the site save money. A well-implemented sustainability plan also helps low-income residents succeed by helping them save money and become healthier, through sustainable site practices like community gardens that increase their access to healthy food, and green cleaning policies and training that reduce their exposure to chemicals in their units and the site’s common areas.
- 49. Questions?