ILLC: Green Roof

GREEN ROOF RETROFITIN ILLC (INTERNATIONAL LIVING LEARNING CENTRE)

CHANHOO KIM I 500183399

GREEN ROOF RETROFIT POTENTIAL in ILLC

ASC720: BUILDING SCIENCE STUDIO I PROJECT PART 5 PG. 2

ABSTRACTPART 1: PREPARATION INTRODUCTION WHAT IS GREEN ROOF? GREEN ROOF BENEFITS GREEN ROOF BYLAW ECO-INCENTIVE PROGRAM

PART 2: EXISTING CONDITION BUILDING CONTEXT EXISTING ROOF

PART 3: DESIGN PROCESS TYPOLOGY DRAINAGE AIR HANDLERS PLANTS

PART 4: EXECUTION EXPLODED VIEW FINISHED CONSTRUCTION TECHNICAL DRAWINGS LIFE CYCLE COSTING

TABLE of CONTENTS



Purpose: The purpose of this report is to illustrate the potential for green roof retrofit in an existing commercial/residential building to managers and other property professionals.

Methodology: This paper addresses the possible benefits of green roof retrofit in ILLC (International Living Learning Centre). Furthermore, it reviews the green roof bylaw in the city of Toronto, as well as the cost benefits by the Eco-Incentive program. Background researches and document reviews were taken in order to perform possible designs for the rooftop of ILLC ground floor.

Findings: The load bearing capacity of existing concrete slab was confirmed through document reviews. A suitable type of green roof was determined in accordance with gravity load, which complies with the existing building.

Practical Implication: LLC (Life Cycle Costing) is taken in account for feasibility study. Green roof benefits both the city and the building by saving costs in storm-water management, air quality, building energy and urban heat island effect. Initial and annual savings are to be studied for further feasibility.

Value: This paper is the first study/proposal of green roof retrofit of buildings in Ryerson University. The findings in this report could provide a model for many aging buildings in this campus.

Keywords: Retrofit, Green Roof, Sustainability, Ryerson UniversityPaper type: Technical Report



PART 1INTRODUCTIONIn the beginning of the last century, group of modernist architects gathered together under the name of CIAM (Congrès International d’Architecture Moderne,) and discussed the future of city planning and architecture. In this historic congregation, lead by Le Corbusier, they envisioned a city crowned by flat roofs with accessible gardens on top. Through out the century, the idea of roof gardens diminished due the high cost and labour, and remained only as a privilege of wealthy living. Nevertheless, today’s barren roofs were never the intention of modernist movement. The modern low-slope roofs are waste of usable spaces, highly deficient in energy consumption and aesthetically displeasing.

The architecture of today demands highly efficient building system that reduces and reuses energy. Engineers, architects and scholars studied and developed technologies to make efficient green roof system that will reduce the energy consumption with ease of installation. It is also the effort of municipality, which initiated green roof by law with significant funding. Today, green roofs are this close to be on the rooftop. As a retrofit project, it is a considerable idea to upgrade an aging building transformed into a sustainable architecture. Green roof retrofit will benefit the environment, as well as the financial expenditures.

ROOF GARDEN OF VILLA SAVOYE

CALIFORNIA ACADEMY OF SCIENCE by RENZO PIANO



WHAT IS GREEN ROOF?

Green roofs are some times called eco-roofs, living roofs, planted roofs or vegetated roofs. There are no technical definition to describe green roof, but generally understood as roof that uses plants and vegetations to improve its performance quality.

Green roofs often divide into two categories: intensive and extensive. Intensive green roofs are more generally understood as typical green roof. It is an accessible roof top garden with deeper, more organic growing mediums. Intensive green roofs are capable to fertile a wide range of plans including shrubs and small trees.

Extensive green roofs, on the other hand, are simpler and lighter type of green roof. Usually, extensive green roofs do not go over 15cm of depth, planted with sedums and low growing plants.

Source: IGRA: A Quick Guide to Green Roofs

PART 1

TOP: EXTENSIVE GREEN ROOFBOTTOM: INTENSIVE GREEN ROOF



PRIVATE BENEFITS

PART 1

Increased Roof LifeDue to the physical, chemical and biological stress on the roofing membranes, the life expectancy of a barren flat roof is only 15 to 25 years. Green roof provides additional protection against UV-radiation, as well as the protection for the waterproofing membrane. Significant layer of soil and vegetation protects the roof in case of mechanical damage such as hail, wind, vandalism and fireworks.

Reduced Noise LevelsGreen roof is a noise reduction solution in urban environment. It reduces sound reflection by up to 3dB and improves sound insulation by up to 8dB. In addition, the vegetation layer shields the roof against electromagnetic waves from transmitting stations.

Thermal InsulationA significant amount of heating loss happens on the roof through conduction because the hot air tends to go up due to the pressure. Green roof is regarded as additional layer of thermal insulation. By increasing the R-value, the mechanical energy consumption can be minimized.

Heat ShieldHaving a green roof on the top is equivalent to having another basement floor. During the summer time, green roof decrease the indoor temperature through transpiration. The overheating of building can be avoided with vegetated roofs; thus, it decreases the energy consumed for air conditioning.

Use of SpaceToday’s barren roofs are mostly not accessible by public. Green roof offers a range of possibilities for space usage. If the technical and construction requirements are met with existing building capability, there is no limit for landscape design, ranging from extensive to intensive roof gardens. Possible spaces usages include recreational roof gardens, roof cafes, and sporting areas.

FLAT BARREN ROOFS ARE INEFFICIENT, DIRTY AND OFTTEN SHORT-LIVED.



PUBLIC BENEFITSHabitat for urban wildlifeGreen roof rigorously promote biodiversity, as wild bees, butterflies and beetles find food and shelter there. Particularly in an urban area, lack of greeneries has significant impact on wildlife species and ecosystem. Green roof compensates for the loss of green areas by providing vegetated green area, which survives its own ecosystem of self-seeding and growth.

Storm-water managementOne of the most advantageous features of the green roof is its capability to store the water and minimize the run-off during the severe storm. Green roof prevents local flooding, and reduces the immediate water run-off by 50-90%. The excess rainwater is filtered and drained off with a temporal delay, which reduces the stress on the sewer system. The water safely returns to the natural water cycle by evaporation of the green roof.

Urban heat island effectGreen areas in urban cities work as natural air-conditioners, absorbing 80% of the energy input; however, in densely populated cities, green areas are rare. Green roofs are an alternative to those lost green areas by providing natural shading effects. Green roofs, if widely implemented, it could reduce the urban heat island effect and improve public heath.

Improved air qualityPlants have the ability to filter and enhance the quality of air. This is one of the reasons why we promote green areas in urban conditions. One square metre of green roof and filter approximately 0.2 kg of air dust and smog particles per year. Inner city air pollutions and quality can be improved by green roofs, and will improve public health.

PART 1

RE-VITALIZATION OF WILDLIFE SPECIES ARE ESPECIALLY VALUBLE IN URBAN CITIES.



GREEN ROOF BYLAW“Toronto is the first City in North America to have a bylaw to require and govern the construction of green roofs on new development.” In May 2009, under the authority of Section 108 of the city of Toronto Act, Toronto City Council adopted the green roof bylaw. The Bylaw applies to the construction of new residential, commercial and institutional. Building permit applications made after January 31, 2010 are in effect of this bylaw, and will apply to new industrial development as of January 31, 2011.

The Bylaw requires green roofs on new commercial, institutional and residential development with a minimum Gross Floor Area of 2,000m2as of January 31, 2010. Starting January 31, 2011, the Bylaw will require green roofs on new industrial development.

PART 1

Gross Floor Area *(Size of Building)

2,000 - 4,999 m2

5,000-9,999 m2

10,000-14,999 m2

15,000-19,999 m2

20,000 m2 or greater

Coverage of Available Roof Space(Size of Green Roof)

20%

30%

40%

50%

60%Note: Residential buildings less than 6 storeys or 20m in height are exempt from being required to have a green roof.

INCENTIVE PROGRAM

The city of Toronto is not only deriving bylaws, but also benefiting the cost of green roof construction. Toronto’s Eco-Roof Incentive Program is designed to promote the use of green and cool roofs on Toronto’s commercial, industrial and institutional buildings, and to help Toronto’s business community take action on climate change. The Eco-Roof Incentive Program provides funds for green or cool roof retrofit projects on existing commercial, industrial and institutional buildings. Eligible green roof projects will receive $50 / square metre up to a maximum of $100,000.



BUILDING

The ILLC is an 11-storey students residence, built in 1987. As a formal hotel brought to Ryerson University 17 years ago, the ILLC accommodates 252 residence students in its extra-large rooms. The ILLC’s second floor houses the Conference Services management department. The residence also features a community kitchenette for making snacks, pop vending machines, a common lounge with cable TV and laundry facilities.

Type of Structure is flat slab, pre-stressed concrete and structural steel. Two-way flat slab with dropped panels system is used from lower basement to ground floor. Shear wall structure system is used from second floor to eleventh floor. The existing roof is constructed with 190mm poured concrete slab with column supports.

PART 2

FLOOR PLAN OF THE EXISTING ROOF TO BE RETROFITTED.



CONTEXT

PART 2

VIEW NORTH: CONSISTING OF MOSTLY RESIDENTIAL APARTSMENTS AND TOWERS

VIEW WEST: DIRECT VIEW TO THE GOULD St. ROGERS COMMUNICATION CENTRE AND MERCHANDIZE BUILDING SIDE BY SIDE.



EXISTING ROOFThe existing roof of ILLC (International Living Learning Centre) displays minor deficiencies including exposed membranes and plant growth. There are no significant problems found related to moisture issues, such as ponding and leaking. Public access to the rooftop, however, is strictly prohibited due to safety, and can only be accessed with administrative permission. The rooftop is covered with ballast material, and there are 6 separate air-handling units.

Though the roof of ILLC is in a good working condition, nature of barren roof is highly inefficient in energy consumption. Considering the large rooftop area (574.5 square metre), the energy loss should be significant; however, there is a better possibility of turning this large area into an accessible amenity space. The second floor of ILLC is currently consisting of several office spaces and unoccupied residential suits. The main user of this floor is administrative staffs and managers.

PART 2

LEFT: EXPOSED FILTER MEMBRANE DUE TO MECHANICAL DAMAGERIGHT: PLANT GROWTH, POSSIBLE SIGN OF MOISTURE COLLECTION

A LARGE ROOFTOP SPACE OCCUPIED ONLY BY SIX AIR-HANDLING UNITS. EXPOSED PIPE MAY CAUSE DAMAGES

AND TRIPPING HAZARD FOR MAINTENECE STAFFS.



TYPOLOGY

Choosing the right type of the green roof in retrofit situation depends highly on the load bearing capacity of the slab and equivalent weight of the system build-up. In ILLC, the slab of rooftop’s load bearing capacity is 1.92kN/sqm, which is converted to 40.1lb/sqft. Among those three types of green roofs, semi-intensive green roof is most suitable choice. The semi-intensive green roof is maximum 40lb/sqft for its weight, thus the existing roof can bear the dead load of soil and plants. It is also a better choice when architectural idea is to include a rooftop amenity space.

The semi-intensive green roof is considerably a better method than the extensive green roof. Extensive green roofs are bare minimum what green roofs can offer. The semi-intensive green roof offers a wider range of plants, and is accessible by public. It has more benefits on space usage, wildlife inhabitance and aesthetics.

PART 3

EXISTING ROOF

Low

Non

*40.1lb/sqft

Low

EXTENSIVEGREENROOF

Low

Moss, Sedum,

Herbs and Grasses

13 - 30 lb/sqft

Low

SEMI-INTENSIVEGREENROOF

Periodically

Grass, Herbs and

Shrubs

25 - 40 lb/sqft

Medium

INTENSIVEGREENROOF

High

Lawn or Perennials,

Shrubs and Trees

35 - 100 lb/sqft

High

maintenece

plant community

weight

cost

*40.1 lb/sqft is the load bearing capacity of concrete slab



DRAINAGE

Green roof is capable of storing a certain amount of water to delay the run off of severe storm-water. To achieve this, the drainage has to be designed to drain the water as slow as possible, and as low sloped as possible. Nonetheless, sufficient drainage is required because standing water causes a long-term risk for membranes, and causes plants to suffocate and rot. In general, a delicate balance has to be determined between the storage and the drainage of run off on green roofs.

PART 3

EXISTING DRAINAGE

NEW DRAINAGE



AIR HANDERS

The roof hosts two large and four medium sized air handlers and air conditioners. It is important to be considerate about connected pipes and ducts. It is cost efficient to minimize the movement of these units. In ILLC, HVAC units are located on centre, and it is hard to maximize the space use with this layout. The architectural decision is to relocate the units off the centre. In doing so, usable spaces are maximized. Gradually sloped layer of vegetated carpet was applied over the units to hide them from the viewer’s site.

The engineer’s inspection is highly suggested, in order to calculate most efficient duct sizing to avoid pressure drops. The financial feasibility issues should also be considered through the administrative decision by staffs and property mangers.

PART 3

EXISTING AIR HANDLERS

RE-LOCATED AIR HANDLERS

THESE AIR HANDLERS ARE RELOCATED AND CAMOUFLAGED WITHIN THE ROOF.



PLANTINGThe roof is divided into five distinct planting zones resulting from different space uses and load capacity. Zone 1 and 2 are categorized extensive green roof to limit the public access, at the same time minimize the dead load stress on the concrete roof slab. Zone 3 is semi-intensive green roof to be able to plant variety of vegetation, but restricted access due to the live load. The Rest of the zones are public accessible semi-intensive green roofs that are designed to become an amenity space.

Biodiversity of plants are strongly advised to be consulted with professional ecologists and landscape designers. The space use of amenity space is a flexible decision of administrative managers; however, too much load could result a stress on the slab.

PART 3

ZONE 1: Extensive Green Roof (not accessible)ZONE 2: Extensive Green Roof (not accessible)ZONE 3: Semi-Intensive Green Roof (not accessible)ZONE 4: Semi-Intensive Green Roof (accessible)ZONE 5: Semi-Intensive Green Roof (accessible)



EXPLODED VIEW

PART 4

Growing mediumFilter fabricWater retention matAeration matRigid insulationRoot barrierWaterproof membraneDense DeckConcrete slab

Growing mediumFilter fabricWater retention matRigid insulationRoot barrierWaterproof membraneConcrete slab

Poured cement floorWood deckingConcrete back-up wallMetal gratingWave



FINISHED CONSTRUCTION

PART 4

The new ILLC greeen roof is covered with wood decking and metal grating on top of thevegetated roof, which gives more flexible accessibility while still maintaining the growth of plants.



FINISHED CONSTRUCTION

PART 4

The new construction of overhang canopy is an open concept shelter. Instead of just being on the rooftop, this will give more enclosed cafe-like atmospher. The Intention is to provide a more friendly and accomodating space to the users.



TECHNICAL DRAWINGS

PART 4

SECOND FLOOR PLAN SCALE 1:400

SECTIONAL PERSPECTIVE



LIFE CYCLE COSTING

PART 4

A simple energy audit has been undertaken through the GBRL (Green Building reseach Laboratory’s website. This website ofers a green roof evergy calculator which gives the annual energy saving result.



BIBLIOGRAPHYWeb Resources“A Quick Guide to Green Roofs.” IGRA Information on Green Roofs. International Green Roof Association (IGRA), n.d. Web. 3 Dec. 2010. <http://www.igra-world.com>.

“GBRL | Home Page.” GBRL | Home Page. Green Building Research Laboratory, n.d. Web. 3 Dec. 2010. <http://greenbuilding.pdx.edu/>.

“Live Green Toronto.” toronto.ca | Official website for the City of Toronto. N.p., n.d. Web. 3 Dec. 2010. <http://www.toronto.ca/livegreen/greenbusiness_greenroofs_eco-roof.htm>.

“toronto.ca | Official website for the City of Toronto.” toronto.ca | Official website for the City of Toronto. N.p., n.d. Web. 3 Dec. 2010. <http://www.toronto.ca/>.

“ZinCo Canada Inc..” ZinCo Canada Inc.. N.p., n.d. Web. 3 Dec. 2010. <http://www.zinco.ca/>.

Electronical RecourcesReport on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto. Toronto: Ryerson University, 2005. Print.

BooksSnodgrass, Edmund C., and Linda McIntyre. The green roof manual: a professional guide to design, installation, and maintenance. Portland, Or.: Timber Press, 2010. Print.

Werthmann, Christian. Green roof: a case study. New York: Princeton Architectural Press, 2007. Print.

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ILLC: Green Roof