Sustainable Design in Miami: Building Envelopes and Life Cycle Assessment


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The presentation summarizes an investigation into regionalism and the design of building envelope systems for low rise affordable housing in Miami and Phoenix. The research involved the application of three platforms: cost, energy modeling, and life cycle assessment in the early stages of design to help the design team make inform decisions about the building envelope system.
Sustainable Design in Miami

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  • My opinion is that low rise multi-family housing will be the primary building type used to densify our cities-So the investigation is about building affordably and sustainably in urban cities-The challenge in cities is that architects are trained to use site orientation as the first tool to affect the energy performance of a building, but within a city we’re often constrained by the urban grid.
  • Investigate the design of building envelopes as a region problem with very context specific solutionsClimate region and city population were the first sets of criteria to determine where to investigateWe know that construction and the operation of buildings has a significant negative impact on the environmentAs populations in our cities grow the need for sustainable affordable housing will increase in importanceThis investigation seeks to isolate the design and construction of the building envelope as the first line of defense in the attempt to improve the performance buildings from the standpoint of the environmentThe investigation requires additional scope boundaries, so I am focusing on low rise (4 story) multi-family housing in an urban context. The climate region currently investigated is hot-humid and the city is Miami which is considered part of the sub-tropicsTypical floor plate indicating circulation and unoccupied areas
  • Cost, energy use modeling and life cycle assessment are the three models that will be overlayed atop one another to assess what the best options are in a specific city within a particular climate regionThere are four environmental indicators that are relevant to this investigations:Greenhouse gas emissionsNon-renewable resource depletionEnergy useWaste production
  • Energy:GWP:Resources:Waste: 3.2 lbs per capita
  • A: 4 and 2%B: 6 and 5%Boston: 11 and 12% (w/o air infiltration)
  • Sustainable Design in Miami: Building Envelopes and Life Cycle Assessment

    1. 1. Jason Tapia, AIA, LEED AP, NCARB, CDT<br />
    2. 2. Presentation Goals<br /><ul><li>Problem
    3. 3. Previous Studies
    4. 4. Method
    5. 5. Scope
    6. 6. Results
    7. 7. Conclusions & Questions</li></li></ul><li>PROBLEM<br /><ul><li>Millions of households in sub-standard housing or spending 50% of their income on housing 1
    8. 8. Affordable housing shortage in U.S.
    9. 9. 2.9 million in urban cities
    10. 10. Population will grow by 15% by 2030 2
    11. 11. In 2003 83% of the US population lived in metro areas 3—which grew at a faster rate than the general population (3.8% vs. 3.3%)
    12. 12. Four states expected to grow the fastest: 1st Nevada, 2nd Arizona and 3rd Florida & 4th Texas
    13. 13. Need for housing that is sustainable AND affordable </li></ul>1 The Department of Housing and Urban Development 2007<br />2 US Census Bureau 2009<br />3 Mackun, P.J. Population Change in Metropolitan and Micropolitan Statistical Areas: 1990 - 2003<br />
    14. 14. PROBLEM<br /><ul><li>Housing stock in the US:
    15. 15. 68% is single family homes and 28% buildings of three stories or taller 1
    16. 16. Of the 28%, ¾ were buildings 3-6 stories in height 1
    17. 17. Multi-family low rise is an important area of research and well suited to address the housing problem
    18. 18. Lower initial costs compared to taller buildings
    19. 19. More diverse structural and material options
    20. 20. Faster construction times
    21. 21. Less skilled labor force</li></ul>Goal<br /><ul><li>Building envelope is the most important building system to positively impact the energy performance of a building
    22. 22. Investigation: compare the performance of conventional building envelopes in affordable housing to alternative systems with higher R values or that are regarded as best practice, by applying a technical evaluation in the early stages of the design process using three platforms:
    23. 23. Cost
    24. 24. Energy performance
    25. 25. Life cycle environmental impacts </li></ul>1 The American Housing Survey 2007<br />
    26. 26. PREVIOUS STUDIES<br /><ul><li>Environmental impacts of individual building materials
    27. 27. Environmental impacts whole structures as the functional unit of assessment
    28. 28. Single family home
    29. 29. Office buildings
    30. 30. Focused on the envelope in different climate regions but only looked at energy performance</li></ul>Gaps:<br />Low rise buildings in the US: evaluating cost, energy performance and life cycle impacts <br />
    31. 31. METHOD<br />Research boundaries:<br /><ul><li>Climate regions investigated: hot-humid and hot dry (the four fastest growing states are in these two regions)
    32. 32. Cities: Miami and Phoenix
    33. 33. Building type: low-rise affordable housing
    34. 34. Owned and operated by developer
    35. 35. Rented (eliminates problem of split incentives)
    36. 36. 4 stories
    37. 37. 2700 sf floor plate
    38. 38. Two circulation cores
    39. 39. 10,700 sf of façade area
    40. 40. 2900 sf of roof area</li></li></ul><li>METHOD<br />Overlay research from three models:<br /><ul><li>Life Cycle Assessment: Gabi
    41. 41. Energy performance modeling: Design Builder
    42. 42. Cost: RS Means Costworks</li></ul>LCA Boundaries<br /><ul><li>Type of LCA: process analysis
    43. 43. Cradle to grave for building envelope assembly
    44. 44. Façade: exterior cladding – interior finish
    45. 45. Roof: membrane – roof structure
    46. 46. Excluded:
    47. 47. Foundation, parapets, floor slabs, interior partitions
    48. 48. On-site construction
    49. 49. Packaging of materials
    50. 50. Impact of labor </li></li></ul><li>Energy use and embodied energy<br /><ul><li>Residential buildings consume 22% of energy in the US 1
    51. 51. Average American family spends about $810 a year on heating and cooling 2
    52. 52. Building envelope represents 26% - 30% of initial embodied energy 3</li></ul>ENERGY <br />Global warming potentials (air emissions)<br /><ul><li>Construction and operation of buildings produces 40% of the country’s CO2 emissions 4
    53. 53. GWP Metric: EPA’s TRACI [Tool for the Reduction and Assessment of Chemical and other Environmental Impacts] </li></ul>GWP<br />Non renewable resource depletion<br /><ul><li>Research has shown that as the population grows, consumption of non renewable resources increases 5
    54. 54. Fossil fuels and other minerals</li></ul>RESOURCES<br />Waste production<br /><ul><li>Construction and demolition waste in 2003 was 170 million tons; 39% was residential construction 6
    55. 55. More waste equals more GHGs such as methane </li></ul>WASTE<br />1 US Energy and Information Administration 2008<br />2 US Energy and Information Administration 2005<br />3 Cole and Kernan 1996<br />4 US EPA 2010<br />5 Sznopek 2006. Drivers of US Mineral Demand<br />6 US EPA 2009<br />
    56. 56. CMU<br />R 6<br />ICF<br />R 22<br />FC SIPs<br />R 40<br />
    57. 57. Wood Frame<br />R 22<br />ICF<br />R 22<br />OSB SIPs<br />R 39<br />
    58. 58. <ul><li>R-Value: CMU 6, ICF 22, SIPS 40
    59. 59. Performance difference in this climate appears insignificant
    60. 60. ICFs perform better because of thermal mass
    61. 61. Florida energy code allows for thermal mass discount (from R13 to 4)
    62. 62. Energy code loosely based on IECC 2007
    63. 63. Single glazed windows, double laminated for impact resistance (hurricane)</li></ul>Excluded from energy model<br /><ul><li>Lighting
    64. 64. Occupancy load
    65. 65. Hot water service
    66. 66. Thermal transfer between</li></ul> zones (adiabatic modeling)<br />
    67. 67. Assumptions for both cities: <br /><ul><li>18.2% glazing ratio
    68. 68. No mechanical ventilation
    69. 69. Only energy required to heat and cool based on heat loss and gain through envelope
    70. 70. Air infiltration modeled differently in two studies: .7 AC/H constant and another study that varied based on envelope type
    71. 71. R-Value: Wood 22, ICF 22, SIPS 39
    72. 72. Arizona code based on IECC 2000
    73. 73. Minimum of R13—conventional outperforms code
    74. 74. Double insulated glazed windows</li></li></ul><li><ul><li>OSB faced SIPs more competitively priced
    75. 75. Windows more than a third of the costs
    76. 76. For ICF wall the forms are 10% of the costs
    77. 77. SIPs are precision engineered to 1/8” tolerance
    78. 78. 8% Difference in cost between</li></ul>ICF and CMU <br /><ul><li>Cost difference attributed to additional labor associated with masonry
    79. 79. 34% Difference between SIPs and CMU</li></ul>1 Data from RS Means 2009 and interviews conducted by investigator<br />
    80. 80. <ul><li>Six LCA models built in Gabi
    81. 81. Steel recycling modeled
    82. 82. Demolition of envelope modeled
    83. 83. Recycling of EPS rigid foam in certain applications
    84. 84. Transportation of materials factored
    85. 85. Maintenance in Use Phases includes:
    86. 86. Window replacement (and recycling)
    87. 87. Roof membrane replacement
    88. 88. Stucco repair
    89. 89. Repainting</li></li></ul><li><ul><li>The process of making cement and steel are the most energy intensive—systems with large amounts of these materials are generally the most energy intensive</li></li></ul><li><ul><li>The production of polyurethane (6.5 inches thick) in OSB SIPs is largest contributor of GWP</li></li></ul><li><ul><li>Cement production relies heavily on quarried minerals:
    90. 90. Clay, limestone and sand
    91. 91. FC SIPs use far less cementitious material</li></li></ul><li><ul><li>Mass of concrete and thickness of the wall impact waste
    92. 92. ICFs are nearly 13 inches thick with finishes
    93. 93. SIPs outperform because of 9 inch thickness and fewer materials (except wood frame)</li></li></ul><li>LCA MODEL DETAIL<br />ICF end-of-life map<br />Carbonation credit<br />Steel recycling credit<br /><ul><li>Landfilling concrete reduces CO2 emissions
    94. 94. Recycling steel reduces environmental impacts</li></li></ul><li>Conventional wood frame envelope<br />Conventional CMU envelope<br /><ul><li>Material sources came from interviews with contractors, suppliers and industry trade groups
    95. 95. Truck was assumed to be primary form of transport for site delivery
    96. 96. Transport from extraction to factory is embedded into Gabi processes</li></li></ul><li>IN PRACTICE<br />$7 per SF & 36 MJ per SF<br />Wood truss<br />Post tension concrete slab<br />$31 per SF & 130 MJ per SF<br />
    97. 97. Conclusions<br /><ul><li>In general thinner wall systems = lower environmental impact
    98. 98. SIPs benefits:
    99. 99. Efficient use of material: interior cladding serves as both structure and paint substrate
    100. 100. Has the greatest potential for “Design for Disassembly”
    101. 101. HOWEVER wood frame construction in Phoenix is less expensive and has a smaller environmental footprint than either alternate system
    102. 102. ICFs perform slightly better but the environmental impact is hard to justify
    103. 103. Recommend that architects in this practice area incorporate cost, BPM and LCA in the early stages of design in order to:
    104. 104. Validate their design decisions
    105. 105. Improve energy performance, reduce costs and negative environmental impacts
    106. 106. Software platforms incorporating cost, BPM and LCA would likely be too complex or reductive</li></li></ul><li>[Sustainable Design in Miami]<br />