Ethan Heil, Graduate Student in Civil & Environmental Engineering at Stanford University Sustainable Urban Systems Symposium Stanford University, June 2016

1. Evaluating sustainability in
low-income, affordable housing
Ethan Heil, Graduate Student

2. Outline
Evaluating sustainability in
low-income, affordable housing
Introduction
What is sustainable housing?
Methods
How can sustainability be evaluated?
Results
How can sustainability feedback enable better designs?

3. What is sustainability?
Evaluating sustainability in
low-income, affordable housing
Sustainable 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
“
”
environmental economic
social
sustainability

4. What is low-income housing?
Evaluating sustainability in
low-income, affordable housing
social
Household income < 80% local median family income
-- or --
Household income < 200% federal poverty line
Demographic designation
Household income = total after-tax income of all household residents
low-income housing

5. What is affordable housing?
Evaluating sustainability in
low-income, affordable housing
economic
Total housing costs < 30% household income
Economic designation
Total housing costs = rent, mortgage, utilities, repairs, insurance, etc.
Household income = total after-tax income of all household residents
affordable housing

6. What is low-income, affordable housing?
Evaluating sustainability in
low-income, affordable housing
economic
social
low-income,
affordable
housing
Affordable housing for low-income households
Often subsidized by the government
90% of new units leverage the Low Income Housing Tax Credit
41% of multifamily housing in the U.S. is subsidized in some way

7. Why low-income, affordable housing?
Evaluating sustainability in
low-income, affordable housing
economic
social
low-income,
affordable
housing
Demonstrated need for new housing development
30 million unit deficit
Only 43% of low-income households live in affordable units
85% of the current affordable housing stock was built before 1990

8. How sustainable is low-income, affordable housing?
Evaluating sustainability in
low-income, affordable housing
Low-income households are less energy efficient and more costly
0
10
20
30
40
50
1000Btu/sf
0.00
0.20
0.40
0.60
0.80
1.00
1.20
$/sf
energy costs by income bracketenergy intensity by income bracket
<$20K $20- $40- $60- $80- $100- >$120K
40K 60K 80K 100K 120K
<$20K $20- $40- $60- $80- $100- >$120K
40K 60K 80K 100K 120K

9. Housing that meets all facets of sustainability
Increased durability and energy efficiency
Reduces operating and maintenance costs
Increased health and wellness among tenants
Greater community resiliency
Green, low-income, affordable housing.
Evaluating sustainability in
low-income, affordable housing
environmental economic
social
sustainability
G.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.

10. How can sustainability be evaluated?
Evaluating sustainability in
low-income, affordable housing
southwest-environmental.co.uk/further%20info/life_cycle_assessment/life_cycle_assessment.jpg
Life cycle assessment
method for quantifying the environmental impacts
created throughout the full life cycle of a product
Life cycle costing
method for quantifying the costs associated with a
product throughout its full life cycle

11. Life cycle assessment for buildings
Evaluating sustainability in
low-income, affordable housing

12. Life cycle costing for buildings
Evaluating sustainability in
low-income, affordable housing

13. Model framework
Evaluating sustainability in
low-income, affordable housing

14. The design process
Evaluating sustainability in
low-income, affordable housing
Early design Detailed design Construction
Designflexibility
maximum
minimum
Design 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

15. Parametric analysis
Evaluating sustainability in
low-income, affordable housing
Geometric parameters + Component parameters
Orientation
Building shape
Length
Width
Number of floors
Window-to-wall ratio Shading
Projection factor
Substructure system
Columns and beams
Cladding
Windows
Doors
Roof structure
Ceiling finishes
Walls structure, insulation, & finish
Floor structure, insulation, & finish
=

16. Case study results
4
6
8
10
12
$6 $8 $10 $12 $14 $16
Lifecycleimpact(millionkgCO2e) Life cycle cost ($million)
Evaluating sustainability in
low-income, affordable housing
Case study in San Francisco, CA
100,000 analyzed designs
1024 possible designs

17. Comparing design decisions
Evaluating sustainability in
low-income, affordable housing
Floor finish options
Wood vs Terrazzo

18. Comparing design decisions
Evaluating sustainability in
low-income, affordable housing
Impact Cost
Initial Operational Life cycle Initial Operational Life cycle
Ceramic 52.2% 59.1% 54.7% 52.6% 75.6% 64.8%
Stone 53.7% 58.8% 55.9% 7.9% 75.4% 15.5%
Concrete Topping 38.9% 58.7% 42.7% 66.8% 75.4% 76.1%
Exposed Concrete 53.3% 58.9% 55.6% 70.0% 75.4% 78.5%
Neoprene 50.8% 44.5% 49.3% 49.1% 34.0% 44.8%
Terrazzo 38.8% 16.8% 29.9% 20.6% 10.1% 11.2%
Vinyl 54.0% 54.8% 54.9% 53.5% 38.3% 50.9%
Carpet 53.7% 40.0% 50.5% 65.0% 12.8% 41.6%
Wood 54.6% 58.6% 56.6% 65.5% 53.0% 67.5%
Floor finish options

19. Comparing design decisions
Evaluating sustainability in
low-income, affordable housing
Impact Cost
Initial Operational Life cycle Initial Operational Life cycle
Ceramic
Stone
Concrete Topping
Exposed Concrete
Neoprene
Terrazzo
Vinyl
Carpet
Wood
Floor finish options

20. Evaluating sustainability in
low-income, affordable housing
Thank you
ethankheil@gmail.com