LIFE CYCLE ASSESSMENT CASE 1
CASE 2 Steel system with Precast double-T
30 year Fiberglass shingles
R-20 Insulation
Pitched Wood Truss with Wood-Decking (R-20 Cavity Insulation)
6” concrete block
2 Layers of GWB with wooden studs @ 24” o.c Wood cladded exterior wall with structural panel sheathing
Concrete block exterior wall with insulation and gypsum board paneling Aluminum framed glass windows
Wooden framed glass windows Precast hollowcore floor Wood joist with plywood decking
4” poured concrete slab
4” poured concrete slab Concrete wall foundation wall with poured concrete footing
Concrete wall foundation wall with poured concrete footing
Precast concrete columns with precast concrete beams This design uses mainly concrete and precast concrete assemblies. The high environmental impact of using concrete has been talked about throughout the LCA class. The idea behind using this method of construction is to test the impact of using concrete. The envelope insulation of this design is in equivalence with the Baseline design.
HSS columns with Glulam beams This design approach uses material assemblies which are more typically used in the Northeastern region of United States. The idea behind using this construction technique is to have a design that has withstood the test of time and at the same time uses materials which are locally available, thus reducing the embodied energy of the building.
Wall Section Wall Section
Roof Section Prefabricated Concrete Panel Roof vs Wooden Truss Roof Aluminum Window Frame vs Wooden Window Frame Concrete Block Wall with Insulation vs Wood Cladded Wall with Cavity Insulation Precast Hollowcore Flooring vs Plywood Decking over Wooden Joists
Section through Case 1 Building
Section through Case 2 Building
Section through column and beam
LIFE CYCLE ASSESSMENT LI F E C YC LE I NVENTORY Assembly
Foundation And Footings
Columns And Beams
Intermediate Floors
Exterior Walls
Windows
Interior Walls
Roofs
Area
9180 sq.ft
7200 sq.ft
7200 sq.ft
3240 sq.ft
1080 sq.ft
4080 sq.ft
7200 sq.ft
Baseline
Crawlspace with a 4” foundation slab, 42” deep concrete cast-in foundation wall, supported on a continuous footing 24” wide and 12” deep
Wide flange columns and wide flange beams
Lightweight steel joists with plywood decking
2x4 Steel studs @16” o.c. with brick cladding, R7-5 CI sheathing, and R-13 cavity insulation + polyethylene membrane. Finished with GWB and paint.
Aluminum window frames
Steel Studs at 24” o.c. with 2 layers of 5/8” GWB for acoustic isolation
Modified Bitumen roof membrane, R-20 Continuous insulation + Polyethylene Membrane, on open-web steel joists with steel decking
Case-1
Crawlspace with a 4” foundation slab, 42” deep concrete block foundation wall, supported on a continuous footing 24” wide and 12” deep
Precast concrete column and precast concrete beam
Precast Hollowcore
8” Concrete block exterior wall with continuous insulation and a polyethylene membrane. Finished with GWB and paint.
Aluminum window frames
6” concrete block with 2 coats of latex paint
Steel roofing system , R-20 Continuous insulation + Polyethylene Membrane, on precast double-T roof slab
Case-2
Crawlspace with a 4” foundation slab, 42” deep concrete block foundation wall, supported on a continuous footing 24” wide and 12” deep
HSS column with glulam beam
Wood joist with plywood decking
2x4 Wood stud @ 16” o.c with wood cladding, wood structural panel sheathing, R-19 cavity insulation + polyethylene membrane. Finished with GWB and paint
Wooden window frames
Steel Studs at 24” o.c. with 2 layers of 5/8” GWB for acoustic isolation
Pitched wood truss with wood decking, 30 year fiberglass shingles, R-20 Cavity insulation + Polyethylene Membrane
L I F E C Y C L E I M PA C T A S S E S S M E N T A N D A N A LY S I S O F R E S U LT S 3000000
200000 180000
2500000
7,000,000
160000
6,000,000
140000
2000000 1500000 1000000 500000
120000
5,000,000
100000
4,000,000
80000
3,000,000
60000
2,000,000
40000
1,000,000
20000
0
0
0 Foundations and Footings
Columns and Beams
Intermediate Floors
Exterior Walls
Windows
Fossil Fuel Consumption
Global Warming Potential
Acidification Potential
Eutrophication Potential
Ozone Depletion Potential
Smog Potential
Interior Walls
Roof
Human Health Criteria
BASELINE LCA IMPACTS: The above chart represents the various environmental impacts of using the mentioned material assemblies in the baseline design. o Foundations and footings are made of poured concrete which has a higher environmental impact than precast concrete blocks. Using this high volume of concrete for footing causes fossil fuel consumption as high as 2705956 MJ. o Roofing causes high fossil fuel impact because of the bitumen roof membrane which goes through several manufacturing processes before reaching its end use and thus consumes more fossil fuel. o Aluminum extraction and aluminum section manufacture is a tedious process which takes place at high fossil fuel consuming factories. Aluminum mines are usually far from site location, which means that an aluminum window frame has to travel more than a locally procured wooden frame. This is what makes aluminum a bad choice in terms of embodied energy. o Although the columns and beams in this design are made of steel, which is an equally high environmental impact material, the quantity of metal used for this relatively small area explains the small percentage of impact caused by this structural assembly. o The other environmental impact indices such as the Global Warming Potential, Acidification Potential and Ozone Depletion Potential to not shoot up to levels as high as Fossil Fuel Consumption because material extraction and manufacture is a fuel consuming and carbon emitting process. However, the other criteria are equally important for sustainability and nature’s harmony and should not be undermined.
Baseline Baseline
Case-1
Case-1
Case-2
Case-2 Fossil Fuel Consumption
Global Warming Potential
Acidification Potential
Human Health Criteria
Eutrophication Potential
Ozone Depletion Potential
Smog Potential
POST DESIGN MODIFICATION LCA IMPACTS: The above charts represents the various environmental impacts after altering some crucial design assemblies from the baseline mode. Least Environmental Impact - Case 2 > Case 1 > Baseline – Most Environmental Impact o Changing the foundation wall material from cast-in place concrete to precast concrete blocks slightly reduces the fossil fuel consumption (by ~10000 MJ) o Replacing wide flange columns and beams with precast columns and beams reduces FFC by ~170000MJ. Using HSS columns and Glulam beams further reduces the FFC by ~62000MJ. o When the initial steel joist with plywood decking floor was changed to a precast hollowcore, the FFC dropped by ~19000MJ. Using wooden joists instead led to a drastic drop of ~230000MJ. o The wood cladded, insulated and finished with GWB wall (Case2) has extremely low impact compared to the brick and concrete walls. o Replacing aluminum window frames with wooden window frames leads a drastic drop of ~350000MJ in FFC. However, wooden frames are not as air tight as aluminum frames and may cause high heating/cooling loads due to infiltration. For this reason, it is better to use aluminum frames. o Interior walls made of 2 layers of GWB with insulation in between is a better option than a wall made of concrete blocks. o Roofing is a high impact member of a building. Using an insulated roof with bitumen membrane or an insulated roof with precast double-T roof panels is very harmful compared to a traditional wood truss roof with insulation. o All in all, wherever wood is used, the environmental impact goes down. Therefore it can be said that Best – Wood > Concrete > Steel - Worst