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Evaluating sustainability in low-income, affordable housingEthan Heil, Graduate Student

OutlineEvaluating sustainability in low-income, affordable housingIntroductionWhat is sustainable housing?MethodsHow can sustainability be evaluated?ResultsHow can sustainability feedback enable better designs?

I will begin this presentation by defining a number of the terms in my title as they pertain to my research,Then I will present a method for evaluating the sustainability of new housing structures, followed by a couple examples of how this method can increase sustainability

What is sustainability?Evaluating sustainability in low-income, affordable housingSustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

- Brundtland Commission, 1983 environmentaleconomicsocial

sustainability

Sustainability can mean different things to different people.In the context of my research, sustainability is related to the intersection of environmental, economic and social impacts.

What is low-income housing?Evaluating sustainability in low-income, affordable housingsocialHousehold income < 80% local median family income -- or --Household income < 200% federal poverty lineDemographic designationHousehold income = total after-tax income of all household residentslow-income housing

Low-income housing is a demographic designation referring to households who earn less than a certain amount per year.For example, a family of 4 making less that $67,000/year in san Francisco is considered low-income

SF 80% area median income = $67,328 (80% of $84,160)Poverty line = $24,300 for a family of 4 = $48,600 (200% of $24,300)

What is affordable housing?Evaluating sustainability in low-income, affordable housingeconomic

Total housing costs < 30% household income Economic designationTotal housing costs = rent, mortgage, utilities, repairs, insurance, etc.Household income = total after-tax income of all household residentsaffordable housing

Affordable housing, by definition is a purely economic designationReferring to when total housing costs are less than 30% of total household income

That being said, the term affordable housing is often used to referred to subsidized, low-income housing.

Maximum household costs (family of 4)= $1215/month ($48,600 / 12 * 30%)

What is low-income, affordable housing?Evaluating sustainability in low-income, affordable housingeconomicsocial

low-income,affordable housingAffordable housing for low-income households

Often subsidized by the government90% of new units leverage the Low Income Housing Tax Credit41% of multifamily housing in the U.S. is subsidized in some way

Affordable housing, as it is commonly used tends to refer to government-subsidized housing for low-income individuals.Several government programs provide funds or incentives to provide affordable housing to low-income residents, including the LIHTC

Why low-income, affordable housing?Evaluating sustainability in low-income, affordable housingeconomicsocial

low-income,affordable housingDemonstrated need for new housing development30 million unit deficitOnly 43% of low-income households live in affordable units85% of the current affordable housing stock was built before 1990

Even, with these government programs, however, theres a significant need for new affordable housing units.This is due to an existing deficit as well as aging infrastructure that will need to be replaced (with 85% of existing affordable housing structures over 25 years old)

How sustainable is low-income, affordable housing?Evaluating sustainability in low-income, affordable housingLow-income households are less energy efficient and more costlyenergy costs by income bracketenergy intensity by income bracket$120K 40K 60K 80K 100K 120K$120K 40K 60K 80K 100K 120K

In addition to being relatively scarce, low-income affordable housing also tends to be energy intensive and costly to tenants (In fact, low-income families spend 20% of their annual income on energy costs compared to 5% for the average household)This represents an opportunity to incorporate more sustainable, green building techniques into new affordable housing projects

These graphs illustrate that low-income households use more electricity and spend more on energy per square foot than higher income households.

Housing that meets all facets of sustainabilityIncreased durability and energy efficiencyReduces operating and maintenance costsIncreased health and wellness among tenantsGreater community resiliencyGreen, low-income, affordable housing.Evaluating sustainability in low-income, affordable housingenvironmentaleconomicsocial

sustainabilityG.A. Byrne, K. Day, J. Stockard, Taking Stock of Public Housing, Washington, DC, 2003.Urban Land Institute, Bending the Cost Curve on Affordable Rental Development, Washington, DC, 2013.W. Bradshaw, E.F. Connelly, M.F. Cook, J. Goldstein, J. Pauly, The Costs and Benefits of Affordable Housing, New Ecol. (2005) 201.M. Brennan, A. Deora, E. Handelman, A. Heegaard, A. Lee, J. Lubell, et al., Lifecycle Underwriting: Potential Policy and Practical Implications, Washington, DC, 2013.C. Harak, Up the Chimney, Boston, MA, 2010.L. Fuhry, J. DeCoursey, T. Bardacke, W. Wells, Green Building Criteria in Low-Income Housing Tax Credit Programs, Santa Monica, CA, 2012.

Introducing green building techniques into low-income, affordable housing can increase sustainability by:Increasing durability, efficiency and health while simultaneously reducing costs for residents and building owners.This in turn leads to greater economic and environmental resiliency in the broader community

- Increased durability and energy efficiency green building promotes these tenants- Reduces operating and maintenance costs durability and energy efficiency reduce long term costs for building owners and tenants- Increased health and wellness among tenants more durable, green materials are healthier + increased building comfort- Greater community resiliency better health and economics lead to greater neighborhood spending power

How can sustainability be evaluated?Evaluating sustainability in low-income, affordable housingsouthwest-environmental.co.uk/further%20info/life_cycle_assessment/life_cycle_assessment.jpgLife cycle assessmentmethod for quantifying the environmental impacts created throughout the full life cycle of a product Life cycle costingmethod for quantifying the costs associated with a product throughout its full life cycle

Life cycle assessment and costing are techniques that can be used to quantify the long-term environmental impacts and costs of new housing developments.This includes multiple stages of the building life cycle, from raw material acquisition, through construction, operation and eventually, demolition

Life cycle assessment for buildings

Evaluating sustainability in low-income, affordable housing

In my framework, I focus on the main drivers of life cycle impacts.These occur in the initial stages, due to building component production and the operational stages due to energy use and maintenance and repair activities.(On-site construction and demolition impacts are small contributors to a buildings overall life cycle impacts)

Life cycle costing for buildings

Evaluating sustainability in low-income, affordable housing

A similar method is used to measure life cycle costs.Initial costs are driven by material, labor and construction costs, whereas operational costs are driven by energy and maintenance expense.Similarly, in this case, costs related to building demolition are not included.

Model framework

Evaluating sustainability in low-income, affordable housing

I wont go into detail, but simply point out that this model calculates the initial costs and impacts (due to construction) followed by the operational costs and impacts (due to energy use and maintenance) which add up to total life cycle costs and impacts

The design process

Evaluating sustainability in low-income, affordable housing

Early design Detailed design ConstructionDesign flexibilitymaximumminimumDesign process

The greatest utility for sustainability feedback occurs during the early design stage Adapted from: Struck, C. and Hensen, J. (2007). On supporting design decisions in conceptual design addressing specification uncertainties using performance simulation

Understanding life cycle costs and impacts is only useful if designers can use this information to make better decisions.For this reason, my framework is focused during the early design stage when designers have the flexibility to make significant design changes.

Parametric analysis

Evaluating sustainability in low-income, affordable housing

Geometric parameters+Component parameters OrientationBuilding shapeLengthWidthNumber of floorsWindow-to-wall ratio ShadingProjection factor Substructure systemColumns and beamsCladdingWindowsDoorsRoof structureCeiling finishesWalls structure, insulation, & finishFloor structure, insulation, & finish

=

Providing life cycle feedback during the early design stage requires a technique called parametric analysisThis technique breaks apart a building into significant parameters which can be combined in different combinations to represent different building designs.

Case study results

Evaluating sustainability in low-income, affordable housingCase study in San Francisco, CA

100,000 analyzed designs

1024 possible designs

Using a case study in San Francisco, I evaluated the life cycle costs and impacts of 100,000 different building designs.Each dot represents one of these designs.

These 100,000 designs represent only a small fraction of the 10^24 (1 million billion billion) possible designs.

Comparing design decisions

Evaluating sustainability in low-income, affordable housingFloor finish options

Wood vs Terrazzo

By looking at different design parameters, we can compare the sustainability of design choices.Comparing the designs with wood and terrazzo floors shows how wood is more likely to exhibit lower environmental impacts and costs.

Comparing design decisions

Evaluating sustainability in low-income, affordable housingImpactCostInitialOperationalLife cycleInitialOperationalLife cycleCeramic52.2%59.1%54.7%52.6%75.6%64.8%Stone53.7%58.8%55.9%7.9%75.4%15.5%Concrete Topping38.9%58.7%42.7%66.8%75.4%76.1%Exposed Concrete53.3%58.9%55.6%70.0%75.4%78.5%Neoprene50.8%44.5%49.3%49.1%34.0%44.8%Terrazzo38.8%16.8%29.9%20.6%10.1%11.2%Vinyl54.0%54.8%54.9%53.5%38.3%50.9%Carpet 53.7%40.0%50.5%65.0%12.8%41.6%Wood54.6%58.6%56.6%65.5%53.0%67.5%

Floor finish options

Using a similar approach, we can estimate the likelihood that a given design decision is better than the average design.Higher percentages signify a greater likelihood that a given design is more environmentally or economically sustainable

Comparing design decisions

Evaluating sustainability in low-income, affordable housing

ImpactCostInitialOperationalLife cycleInitialOperationalLife cycleCeramicStoneConcrete ToppingExposed ConcreteNeopreneTerrazzoVinylCarpet Wood

Floor finish options

A heat map of the previous values provides an easier method for visualizing the relative sustainability of design choices. Here, we can see that wood and stone are the most environmentally sustainable design choices. Concrete, ceramic and wood offer the most economically sustainable choices.

(my hope is that) This methodology gives designers the tools to properly evaluate the tradeoffs of green design decisionsThat can increase environmental and economic sustainability through increased building durability and energy efficiency

Evaluating sustainability in low-income, affordable housingThank youethankheil@gmail.com

(my hope is that) This methodology gives designers the tools to properly evaluate the tradeoffs of green design decisionsThat can increase environmental and economic sustainability through increased building durability and energy efficiency