benefit cost analysis of green roofs for multifamily high-rise facilities in portland, oregon

BCA of Green Roofs for Multifamily High-Rise Facilities in Portland, Oregon

Benefit Cost Analysis of Green

Roofs for Multifamily High-Rise

Facilities in

Portland, Oregon

Hassalo on Eighth, Portland, OR.

Mona Qaddoumi

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June 13, 2015

Marylhurst University

Natural Resource Economics

Table of Contents

Executive Summary 3

Introduction 4

Literature Review 5

Assumptions and Outputs 5

Methodology 6

Data Requirements 7

Data Shortcomings 8

BCA Findings 9

Project Analysis 9

Conclusions 15

References 17

Appendix A 19

Appendix B 21

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Appendix C 23

Appendix D 25

Executive Summary

Throughout this Benefit Cost Analysis the fundamental elements to consider go

beyond that which is quantifiable in dollar terms. Even though green roofs have been

around for centuries, modern implementation is relatively new. The costs and benefits

include a number of social, environmental and fiscal factors. However, even with the

data available, there are a number of shortcomings that affect the over efficacy of green

roofs.

Initial costs of installing a green roof are dependent on the type of green roof to be

installed as well as the square footage of the roof. National averages have been applied

into the cost analysis as it relates to this specific project of a 40,000sqft semi-intensive

green roof. Additional maintenance costs are also included as tending to plant life is

needed on a regular basis.

Benefits of installing a green roof take in consideration hard statistics such as

energy savings and stormwater management. It also considers more objective, but still

statistically monetized environmental applications such as, air quality improvements,

carbon sequestering and habitat formation for invertebrates and birds.

Outside of concrete fiscal benefits are the non-monetized social, environmental

and economic benefits of installing a green roof. These include job creation,

marketability and increased urban habitat. Marketability could potentially be monetized,

but there is a lack of research on rent and occupancy rates of multifamily buildings

associated with green roofs.

This Benefit Cost Analysis found that even over a 40-year period and the

factoring in of the replacement of a black roof (at 20 years), green roofs fall short on hard

ROI. The fact of the matter is installing green roofs go beyond fiscal investments. The

overall benefits outweigh the costs as can be seen within this report. My hypothesis is

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that the government will need to motivate the enforcement of green roofs to improve the

lives of its people and to strengthen the future economy.

Introduction

Objective

The objective of this Benefit-Cost Analysis is to identify the associated costs and benefits

of installing a semi-intensive green roof on a multifamily high-rise building. This report

will include private and public benefits that this practice has for its inhabitants and the

local community. It will generate a cost analysis by looking at the benefits to show not

only monetary savings, but also social and

environmental savings as a result from its

function.

Scope of Work

This analysis will take specific data of the Green

Roof projects in Portland, Oregon, as well as more

general data from other projects to identify cost

benefits. It will look into the costs of creating and

maintaining a semi-intensive green roof by

researching averages by square foot. The semi-

intensive green roof will have 6-10 inches of soil

with a diversity of plant life over a 40,000sqft

surface.

The benefit cost analysis will consider

many major components. These components will

include, energy efficiency, roof durability and

longevity, noise reduction and marketability.

Other benefits will include, water diversion, storm

water management, air quality and carbon sequestering (Green Roofs for Healthy Cities,

Key Findings

The longevity of green roofs out

performs the traditional black

roofs by 20 years.

Initial and long-term private cost

benefits include, energy saved,

replacement costs saved, federal

incentives and direct stormwater

management.

Initial and long-term public cost

benefits include, improved air

quality, improved water quality,

carbon sequestering and reducing

stormwater runoff.

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2014). This data will provide an analysis of the cost benefits and come to a conclusion of

green roof efficacy.

History

Green Roof technologies were modernized in the early seventies in Germany

and then later further developed in the late eighties to reduce costs and refine

techniques (Jörg Breuning & Green Roof Service LLC, 2015). As a revived ancient

system, Green Roofs were originally intended to restore nature and protect roof

membranes, but as the technology flourished scientific research began to find a

number of other benefits including, "waste diversion, storm water management,

improved air quality, energy efficiency and much more" (Green Roofs for Healthy

Cities, 2014).

Literature Review

Key data findings for this Benefit Cost Analysis were pulled from various BCA

reports conducted by the City of Portland, the United States General Services

Administration (GSA) and Green Roofs for Healthy Cities. Each report touches on

monetized findings based on green roof size and type. The report conducted by the GSA

is cited in the Green Roofs for Healthy Cities report and the GSA report used over 200

studies to compile their information.

Additional information was retrieved from various businesses, building websites

and green roof company websites. Marketability information includes an online survey

conducted on Facebook asking two questions relating to the willingness-to-pay for a

green roof on top of a high-rise multifamily facility. Dynamic efficiency includes

information retrieved from a phone interview with Amy Chomowicz, the program

director for the City of Portland’s Ecoroof Program. Each resource will be cited on the

reference page. The survey components will be explained in Appendix D.

Assumptions and Outputs

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Information provided for the data comes from a number of sources including,

local and federal reports as well as specific city or state findings other than Portland,

Oregon. Specific data sets as well as average data sets between listed sources are used

for the analysis in this BCA.

Methodology

Cost Effectiveness

When considering a green roof for a multifamily high-rise facility, cost effectiveness

will need to be taken into consideration. Owners of these building types typically regard

them as financial investments, so it is important to show the cost effectiveness and

benefits to installing a green roof to further prove its efficacy. Included in this analysis

will be the consideration of the following data in private cost effectiveness:

Installation costs/square feet of green roof compared to black roofs

Green roof versus black roof longevity (years before replacement)

Annual maintenance cost differences

Energy efficiency increases associated with green roofs

Stormwater management costs

Federal incentives

The timeline to consider will be 40 years, which is the average lifespan of a green

roof. This will show the costs of installing and maintaining a green roof compared to a

black roof as well as the benefit of not having the replacement costs of a black roof at the

20-year mark.

Green roofs offer a number of public benefits in addition to the private benefits to

the direct owner and inhabitants of the building. Data found from DC Greenworks, The

City of Portland Ecoroof Program and the GSA’s Green Roof Benefits and Challenges

report are incorporated into the assumptions and benefits of this analysis. These benefits

include:

Improved Air Quality

Stormwater Improvements

Carbon Sequestering

Marketability

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In addition, non-monetized public benefits were also analyzed for the sake of

further understanding the total system benefit. These benefits include:

Job Creation

Increased Urban Habitat

Aesthetics and Biophilia

Data Requirements

When considering green roofs this analysis will look at private, public and

economic benefits.

Identify Incentives: (Doshi, H. & Peck, S. n.d.)

Design and installation grants

Tax and fee rebates,

Preferable zoning allowances

Identify Costs: Green Roofs for Healthy Cities: Working Draft 13 (Doshi, H. & Peck, S.

n.d.)

Cost of a cubic meter or cubic foot of stormwater

Cost of energy

Cost of annual maintenance

Cost of initial investment

Cost of replacement of black roof

Calculate the benefits as it relates to: (GSA GREEN ROOF BENEFITS AND

CHALLENGES, 2011).

Stormwater management

Biodiversity and habitat

Energy

Marketability

Air quality

Aesthetics and quality of life (biophilia)

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Job generation and economic development

Roof longevity

Carbon sequestering

Other data to consider: (GSA GREEN ROOF BENEFITS AND CHALLENGES,

2011)

Building structural requirements

Historic buildings

Codes and standards

Contractor skills

Handling and knowledge of plants

Safety training and personnel

Plant establishment

Leaks and leak detection

Plant loss

Wind scour

Root penetration and biodegradation

Data Shortcomings

Gathering data on storm flow dynamics is typically only one to three years and

according to the City of Portland’s 2008 study of 40,000sqft, 5-story extensive green roof

with 5inches of soil, they had an initial cost savings associated with Avoided Stormwater

Systems Improvement of $16.334 versus the City of Toronto’s study which was only

$2.368 (Hitesh & Peck (n.d.). Data averages from stormwater will depend on the

environment’s average rainfall as well as the type of green roof (i.e., intensive or

extensive).

In addition, most data for this analysis was pulled from GSA’s report from 2011,

costs and benefits may have increased since then. Other shortcomings include, lack of

specific data related to marketability, soil type, irrigation type, roof membrane statistics

and specific information related to maintenance costs.

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BCA Findings

The present value (PV) benefits totaled to $553,698.54 for the analysis of a

40,000sqft semi-intensive green roof over a 40-year period, in addition to a present value

(PV) of costs of $1,097,390.25. The benefit cost ratio came to 0.504559. Included in this

analysis were the monetized environmental benefits to installing a green roof. Also

included, was the added benefit of not having to replace the roof after 20 years, which is

the average lifespan of a black roof.

The present value (PV) of costs came to $1,097,390.25. This data was calculated

by taking the initial and annual costs associated with a 40,000sqft semi-intensive green

roof. An inflation rate of 3% was added to each year after the initial year for annual

replacement costs. A discount rate of 4% was added to the annual present value of

replacement costs. The discount rate takes into account unknown future costs such as,

soil replacement, drought, plant loss, plant scour and possible leaks that need repairing.

The present value (PV) of benefits came to $553,698.54. Total benefits would

average $19,808.60 annually and include private benefits associated with energy savings,

stormwater management, federal incentives and the correlated costs of longevity as it

compares to black roofs. Public benefits include avoided stormwater management costs,

air quality improvements and carbon sequestering.

Project Analysis

Instrument Target Addressee Regulation Area

Standard: Building green roofs on the top of multifamily housing high-rise facilities

Increase efficiency of stormwater management

Increase roof longevity

Improve air

Multifamily High Rise Communities

Renters Owners Developers

Portland, Oregon and the greater metro area

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quality Create a

biospace from residents

Cost Effectiveness, Economy Efficiency & Non-Monetized Benefits

Improved Air Quality and Carbon Sequestering

Green roofs improve air quality in urban areas. Vegetation growth can sequester

carbon dioxide as well as improve or remove Particulate Matter, Nitrogen Oxide

Compounds and Sulfur-Oxygen Compounds (Hitesh & Peck, n.d.). “Carbon [dioxide] is

sequestered in plants through photosynthesis, and it is stored in the soil and roots” (GSA,

2011). Plants from green roofs can intercept Nitrogen Oxide and Particulate Matter,

which both cause pollution. By removing these pollutants from the air as well as

lowering greenhouse gases, such as Carbon Dioxide, green roofs can not only help

improve human health, but could also help slow global warming.

Stormwater Improvements

In urban areas, stormwater management has become increasing complicated. Sewer

overflows, water processing and acid rainfall all affect the health and costs of both the

private and public sector. Green roofs have a great impact on stormwater management.

According to the GSA’s report, “Green roofs can reduce the rate of runoff from a roof by

up to 65%” as well as, “catch and permanently retain the first ½ to ¾ inch or rainfall”

(2011).

Underground pipes, private water systems and public water management affect both

the owner of the building as well as the taxpayer on a monetary basis. By limiting the

amount of water in the system, a city can lower costs associated with regular

maintenance.

Green roofs also have demonstrated to be effective in reducing pollutants in water,

thus creating cleaner run-off. However, other studies have shown that the opposite can

occur. Added compounds from soil and fertilizer can contaminate surface water causing

a decrease in water purity (GSA, 2011).

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Marketability

The marketability of green roofs within the private enterprise is promising. Recently,

there has been a dramatic increase of multifamily high-rise facilities in Portland with

LEED certifications as well as specific targeted advertising associated with sustainability.

This ‘Sustainable Branding’ is not just limited to real estate; many companies have

adopted Corporate Social Responsibility agendas in addition to implementing sustainable

programs.

From a willingness-to-pay (WTP) average of nine individuals surveyed online via

Facebook, there was an overall inclination towards renting from a building with a green

roof. Six out of the nine participants were willing to pay $50 or more per month for

access to a green roof. Three were willing to pay $75-$150 more per month. These

additional benefits could be added to the BCA; however, more data with a larger

demographic would be needed.

Job Creation

Deciding to install a green roof versus a black roof will help stimulate the

economy. It will add jobs associated with both the initial costs as well more long-term

jobs associated with the maintenance costs. Job creation helps to sustain an economy and

strengthen a community.

Urban Habitat

In urban environments, most native wildlife suffers from loss of habitat. By

adding a green roof to a high-rise building it will “attract species including birds and

invertebrates. [Semi-Intensive and] Intensive roofs typically support a greater diversity

of rare bird species than extensive roofs” (GSA, 2011).

Aesthetics and Biophilia

Many studies show that increased access to nature can help improve mood and

productivity. According to a study from the University of Melbourne, “Subjects who

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took a 40-second break from a demanding task to gaze at an image of a green roof

improved performance and accuracy when they continued with the task” (Ashford, 2015).

This phenomenon is outlined in concept of Biophilia. Biophilia is the hypothesis that

people are mentally and physically affected by the presence or lack of nature (Rogers,

2015). This concept shows the direct benefits of adding a green roof to a building.

Aesthetics also plays a role in human mood and personal pride. Most people

would much rather look at a garden, than black asphalt. Specific to multifamily housing,

tenants can feel a sense of pride when bring guests over. In addition to these sentiments,

aesthetics can also increase property value. People will typically pay more for something

they view as beautiful.

Fairness

Standard application of this type of project would be applied to building owners and

developers of multifamily high-rise facilities. The benefits of this type of project affect

the following individuals, companies and institutions:

To building owner(s) or developer-by increasing the initial costs of construction

and annual maintenance, while also reducing costs of annual energy consumption,

stormwater management and roof longevity.

To the builder, architects and general contractors-by increasing costs, production

time and the hiring of plant/green roof specialists.

To the building occupants-by improving mental and physical health as well as

productivity.

To the green roof specialists and contractors-by increasing their sales and

portfolio as well as possibly gaining new insight on how to achieve results in a

more cost efficient way.

To municipality-by decreasing associated costs with stormwater management and

related new construction infrastructure costs (GSA, 2011).

To the community-by increasing aesthetics, job creation and increasing

biodiversity (GSA, 2011).

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Dynamic Efficiency

The City of Portland no longer offers the incentive of $5/sqft to build a green

roof. As of right now they do not anticipate that to change, however, an increase in

funding for education related to the benefits of green roofs is being considered.

(Chomowicz, 2015). Educating potential tenants and investors on the benefits for

installing a green roof is the first step in growing this practice. Green roofs have the

potential to add value to the property in many different ways. By understanding the long-

term cost benefits, investors can up-sell their building to future buyers. In addition to the

basic modern and known cost savings, future environmental concerns may stimulate new

government tax rebates and incentives related to green roofs, thus further accumulating

cost savings.

At this point, green roofs are not mandatory, but with a rapidly increasing demand

for multifamily housing and a disappearing green landscape, there may be a place for it in

the future. This analysis describes the known and modern practices of green roof

installation for large flat rooftops. Future practices may become more cost effect through

availability and innovation. According to Lux Research innovations in installation and

maintenance costs of green roofs could be cut by 28% by 2017 (Lux Research Inc, n.d.).

There are a number of reasons why someone would invest in this type of project.

In Portland, Oregon there has been a rapid expansion in multifamily housing as well as an

influx of relocating out of state residents. To differentiate from the competition, and to

stay within alignment of the cities’ well-known environmental interests, development

companies are consistently one-upping each other on technological advancements for

sustainability.

For example, Hassalo on Eighth is one of the newest additions to the multifamily

industry here in Portland. This property consists of three buildings with close to 700

livable units as well as retail space; it will be the largest multifamily facility in the

Portland Metro Area. Their front page slogan on their website reads, “Portland’s Newest

Neighborhood, An eco-community, Drawing us together” (American Assets Trust, 2015).

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They also have a constantly updating graph showing the sustainable and environmental

investments made during the construction of the buildings. This is a testament to green

roof marketability. Investors can utilize sustainability features to their buildings as an

enticement for future residents

Moral Considerations

For green roofs, moral considerations would include social and environmental

wellness. Increasing our application of personal well being into business decisions will

help facilitate positive moral values.

Dependability

Dependability relates to the risks and uncertainty that the project will meet the

standards and cost effectiveness stated in the proposal. With construction projects, many

times initial costs can be greater than expected because of new information found when

deconstructing certain parts of a building. In the long run, that data is consistently

beneficial, as long as the green roofs are well maintained.

Complications include:

Plant loss

Wind Scour

Root Penetration and Biodegradation

Building Damage due to Improper Installation

Uncovering other building problems during installation (dry rot, infestation,

improper building codes)

Uncovering building upgrades needed to properly install and maintain the ecoroof

Resident compliance and care (with access to the roof, will the residents abuse the

area?)

Political Acceptability

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This type of project does not have huge implications for politics, yet. Partial or

full green roofs could be a great addition to codes for new construction and old buildings

that generate too much waste. The entirety of benefits analyzed in this BCA for green

roofs shows an enormous value to our municipalities. Green roofs can significantly

lower stormwater management costs as well as improve air quality in increasingly

crowded urban areas. Indirectly, this could improve the mental and physical health of the

community. This would add an enormous benefit if it could keep high cost healthcare,

such as, asthma related emergencies out of the ER, especially for patients who cannot

afford treatment.

Flexibility

Ecoroofs will change over time due to the plants growth, weather conditions and

natural shifts in the buildings movement. Changing elements will include:

Plant loss

Wind Scour

Root Penetration and Biodegradation

Property Rights

For this project the property rights will be relatively cut and dry. The target

market is privately owned multifamily high-rise facilities. There may be times were

multiple investors own the building, in which all or the majority will need to be on board

for the initial extra expense of a green roof.

Conclusions

The total values constructed in this analysis only give a glimpse into the entire

picture of building a green roof. In the end the monetary costs of installing a green roof

are greater than the monetary benefits. However, it is incredibly clear that many of the

benefits to green roofs cannot be properly monetized. More research will need to be done

to identify hard statistics to justify installing a green roof.

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The sum of benefits versus costs shows the most value to government institutions.

The real incentive to build a green roof is to increase the quality of life and activate the

economy. Investing in green roofs is not just an investment in a product that can extend

the life of the roof or add additional maintenance costs to the budget; it is an investment

for the future.

References:

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American Assets Trust. (2015). Hassalo On Eighth. [Website]. Retrieved From:

http://hassalooneighth1.tru-m.com/?utm_campaign=OMG+-

+Apartments&utm_source=google&utm_medium=ppc&utm_term=hassalo+on+eighth&

utm_content=1368098x696696351324719332

Ashford, K. (2015). Looking At Green Roofs May Boost Your Work Productivity.

Forbes Magazine Online. [Website]. Retrieved From:

http://www.forbes.com/sites/kateashford/2015/05/29/green-roofs/

Balducci, P. (n.d.) Unit 3: Environmental Policy Instruments. [Lecture]. Retrieved from:

https://moodle.marylhurst.edu/pluginfile.php/343712/mod_book/chapter/42732/

Environmental_Policy_Lecture_Part_1.swf

Chomowicz, A., Personal Communication, June 5, 2014.

City of Portland, Oregon. (2015). Ecoroof Incentive. [Website]. Retrieved From:

https://www.portlandoregon.gov/bes/48724

GSA Green Roof Benefits And Challenges. (N.D.). The Benefits and Challenges of

Green Roofs on Public and Commercial Buildings. [Website]. Retrieved From:

http://www.gsa.gov/portal/mediaId/158783/fileName/The_Benefits_and_Challenges_of_

Green_Roofs_on_Public_and_Commercial_Buildings.action

Hitesh, D. & Peck, S. (n.d.). Methods for Estimating Economic Public Benefits from

Regional Implementation of Green Roof Technology-Working Draft Paper for Review.

[Website]. Retrieved From: http://www.greenroofs.org/resources/Doshi&Peck.pdf

Green Roofs for Healthy Cities. (2014). Green Roof Benefits. [Website] Retrieved from

http://www.greenroofs.org/index.php/about/greenroofbenefits

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Jörg Breuning & Green Roof Service LLC. (2015). Green Roof Technology: Form and

Function. History. [Website]. Retrieved from

http://www.greenrooftechnology.com/history-of-green-roofs

Lux Research (n.d.). Innovation Will Drive Costs of Green Roofs and Walls by 28% in

2017. [Website]. Retreived From:

http://www.luxresearchinc.com/news-and-events/press-releases/read/innovation-will-

drive-costs-green-roofs-and-walls-28-2017

Rafida, S. & Rahman, A. (n.d.). Green Roofs as Urban Antidote: A Review on Aesthetic,

Environmental, Economic and Social Benefits. [Website]. Retrieved From:

http://www.academia.edu/2283321/Green_roofs_as_urban_antidote_A_review_on_aesth

etic_environmental_economic_and_social_benefits

Rogers, K. (2015). Biophilia Hypothesis. [Website]. Retrieved From:

http://www.britannica.com/science/biophilia-hypothesis

Stamats Communications, Inc. (2014). Calculating the Life Cycle Cost of a Roof.

[Website]. Retrieved From:

http://www.buildings.com/article-details/articleid/13816/title/calculating-the-life-cycle-

cost-of-a-roof.aspx

Plant Connection Inc. (2015). Green Roof Legislation, Policies & Tax Incentives.

[Website]. Retrieved From: http://myplantconnection.com/green-roofs-legislation.php

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Appendix A

Assumptions and BCA Outputs

PV Benefits $553,698.54 PV Costs $1,097,390.25 Benefit/Cost Ratio 0.504559 Benefits Total Annual Total Timeframe Energy Savings $15,423.21 Annual Stormwater improvement $8,800.52 Initial Avoided Stormwater System Operating and Maintenance $1,330.48 Annual Air Quality (Particulates) $3,025.18 Annual Carbon Dioxide Sequestering $29.73 Annual Habitat Creation (US Biodiversity Banking System) $141.60 Initial Federal Incentives $72,000.000 Initial Costs Total Cost of installing a semi-intensive green roof per sqft (labor, materials and irrigation included) $727,600.00 Initial Additional Annual Maintenance Costs for semi-intensive green roof per square feet $11,200.00 Annual Assumptions Square footage of roof 40,000 Square Meters of roof 3716.435938 Square Foot/Square Meter 10.763 Time Horizon 40 Years Discount Rate 4% Inflation Rate 3% Cost Elements Measurement Timeframe Source Cost of installing a semi-intensive green roof per sqft (labor,

$18.19 Initial GSA year

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materials and irrigation included)Additional Annual Maintenance Costs for semi-intensive green roof per square feet $0.28 Annual GSA Benefit Elements Measurement Timeframe Source

Energy Savings Cost per kWh/m2/year $4.15 Annual

Hitesh, D. & Peck, S. (n.d.). Methods for estimating economic public benefits from regional implementation of green roof technology-working draft paper for review

Stormwater Improvement per m2 $2.368 Initial


Avoided Stormwater System Operating and Maintenance per m2 $0.358 Annual


Air Quality (Particulates) per m2 $0.814 Annual

Hitesh, D. & Peck, S. (n.d.). Methods for estimating economic public benefits from regional implementaion of green roof technology-working draft paper for review

Carbon Dioxide Sequestering per m2 $0.008 Annual

Hitesh, D. & Peck, S. (n.d.). Methods for estimating economic public benefits from regional implementaion of green roof technology-working draft paper for review

Habitat Creation (US Biodiversity Banking System) Initial Savings per m2 $0.038 Initial GSAFederal Incentives per sqft $1.800 Initial

Plant Connection Inc. Green Roof Legislation, Policies & Tax Incentives

Cost of not paying for second conventional roof - Year 20 benefit $170,000

Once every 20 years Choice Roof Contractors

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Appendix B

Annual and Present Value Costs

Square Foot 40,000 Initial Investment $727,600.00 Annual Cost $11,200.00 Discount Rate 4% Inflation Rate 3%

Year Annual Replacement CostsAnnual Present Value of Replacement

Costs0 $727,600.00 $727,600.001 $11,536.00 $11,092.312 $11,882.08 $10,985.653 $12,238.54 $10,880.024 $12,605.70 $10,775.405 $12,983.87 $10,671.796 $13,373.39 $10,569.187 $13,774.59 $10,467.558 $14,187.82 $10,366.909 $14,613.46 $10,267.2210 $15,051.86 $10,168.5011 $15,503.42 $10,070.7312 $15,968.52 $9,973.8913 $16,447.58 $9,877.9914 $16,941.00 $9,783.0115 $17,449.24 $9,688.9416 $17,972.71 $9,595.7817 $18,511.89 $9,503.5118 $19,067.25 $9,412.1319 $19,639.27 $9,321.6320 $20,228.45 $9,232.0021 $20,835.30 $9,143.2322 $21,460.36 $9,055.3123 $22,104.17 $8,968.2424 $22,767.29 $8,882.0125 $23,450.31 $8,796.6126 $24,153.82 $8,712.0227 $24,878.44 $8,628.2528 $25,624.79 $8,545.2929 $26,393.53 $8,463.1230 $27,185.34 $8,381.7531 $28,000.90 $8,301.1532 $28,840.93 $8,221.3433 $29,706.15 $8,142.2834 $30,597.34 $8,063.9935 $31,515.26 $7,986.4536 $32,460.72 $7,909.6637 $33,434.54 $7,833.61

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38 $34,437.57 $7,758.2839 $35,470.70 $7,683.6940 $36,534.82 $7,609.80

PV Costs $1,097,390.25

Appendix C

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Annual and Present Value of Replacement Benefits

Square Feet 40000 Initial Savings $80,942.12 Annual savings $19,808.60 Discount rate 4%

YearAnnual

Replacement Benefits

Annual Present Value of

Replacement Benefits

Replacement Costs of

Traditional Roof

0 $80,942.12 $80,942.12 -1 $19,808.60 $19,046.73 -2 $19,808.60 $18,314.17 -3 $19,808.60 $17,609.78 -4 $19,808.60 $16,932.48 -5 $19,808.60 $16,281.23 -6 $19,808.60 $15,655.03 -7 $19,808.60 $15,052.91 -8 $19,808.60 $14,473.95 -9 $19,808.60 $13,917.26 -10 $19,808.60 $13,381.98 -11 $19,808.60 $12,867.29 -12 $19,808.60 $12,372.40 -13 $19,808.60 $11,896.53 -14 $19,808.60 $11,438.97 -15 $19,808.60 $10,999.01 -16 $19,808.60 $10,575.98 -17 $19,808.60 $10,169.21 -18 $19,808.60 $9,778.08 -19 $189,808.60 $90,091.22 $170,000 20 $19,808.60 $9,040.39 -21 $19,808.60 $8,692.68 -22 $19,808.60 $8,358.35 -23 $19,808.60 $8,036.87 -24 $19,808.60 $7,727.76 -25 $19,808.60 $7,430.54 -26 $19,808.60 $7,144.75 -27 $19,808.60 $6,869.95 -28 $19,808.60 $6,605.72 -29 $19,808.60 $6,351.66 -30 $19,808.60 $6,107.36 -31 $19,808.60 $5,872.46 -32 $19,808.60 $5,646.60 -33 $19,808.60 $5,429.42 -34 $19,808.60 $5,220.60 -35 $19,808.60 $5,019.81 -36 $19,808.60 $4,826.74 -

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37 $19,808.60 $4,641.09 -38 $19,808.60 $4,462.59 -39 $19,808.60 $4,290.95 -40 $19,808.60 $4,125.92

Total $1,043,286.26 PV benefits $553,698.54

Appendix D

24


Individually Developed Survey

I. Format Used

a. Online Survey via Facebook (posted on main timeline as well as in St.

John’s Gardening and Permaculture Group)

II. Survey Questions:

a. If you are renting in an urban area would you be wiling to pay extra each

month for access to a green roof?

b. If so, how much more a month would you be willing to pay?

III. Associated Feedback

a. Nine individuals responded

b. Ilko, Laurie, Jannae and Ben all had contingencies of being allotted some

space to use for urban agriculture

Individual’s Name Monthly Amount Willing to Pay for Green Roof

Lydia $50-$150/monthMaeleigh $50-$150/monthMegan $50/monthIlko $25-$50/monthBen $25/monthAlex $25/monthJannae $25-$75/monthScott $15/monthLaurie $50/month

25

benefit cost analysis of green roofs for multifamily high-rise facilities in portland, oregon

Documents

bca of green roofs

enforcement of green

efficacy of green roofs

type of green roof

sqft semiintensive green

benefitcost analysis

multifamily highrise

project analysis