DUNESIDE CLIMATE CENTRE
CHOSEN
CONSTRUCTION
07.04 w a l l c o n n e c t i o n s . optimizing the composition
overall
structural
As a result of the preliminary LCA analysis (pages 70-71), two wall build-ups have been made. One of the walls uses the locally available material straw as insulation and is based upon the principles of the EcoCocon panels, that are both load-carrying and insulating (EcoCocon, n.d.). The other wall has wood fibre batts as insulation and uses a traditional construction technique with load-bearing beams and columns of construction wood, also chosen through the preliminary analysis. The two walls are evaluated based upon construction investigations and an LCA. The analysed walls therefore contain the layers as presented in the details (figure 61), whereas the wood fibre wall includes construction wood, representing the load carrying beams and columns. STRAW PANEL If using the straw panel principle, the load-bearing construction will be placed in the exterior walls, making the wall thicker and less accessible when designing for disassembly.
The two walls both obtain recommended u-values for building class 2020 (Rockwool, n.d.) and are diffusion permeable (fig. 61). Both reeds and wood are considered as exterior façade materials, however in this case, wood is chosen as exterior material for both walls, as it therefore is ensured that the u-value is obtained regardless.
WOOD FIBRE The straw panel stand as both insulation layer and load-bearing element, on which the remaining layers are mounted.
GWP Wood fibre wall
EcoCocon wall
DETAIL The wall has been designed to be diffusion permeable, meaning that moisture can transport itself through the construction. If the saturation pressure does not cross the line of 3
4
5
6
1. 2. 3. 4. 5. 6.
2000 1800 1600
Clay plaster, sd=0,05m Clay panels, sd=0,36m Wood fibre insulation (95mm), sd=1m Paper based vapour retarder, sd=5m Wood fibre insulation (200mm), sd=1m Hunton Windproof, sd=0,42m
1400
Saturation pressure
1200
Vapour pressure
1000 800 600
DETAIL Placing the load-bearing construction on the interior and using wood fiber as insulation, allows for smaller walls and easier disassembly. 12 3
4
5
6
1. 2. 3. 4. 5. 6.
2200 2000 vapour pressure (Pa)
12 2200
vapour pressure (Pa)
Both walls can easily be assembled and disassembled, just as they can easily be connected to floor and roof constructions. The LCA results clarify that the wood fibre wall is the better solution focusing on the majority of the environmental impact indicators. Focusing on the global warming potential being of interest when focusing on climate change, the wood fibre wall has an impact smaller than half of the EcoCocon wall. The results for the other indicators can be found in appendix 09.02.
1800 1600
Clay plaster, sd=0,05m Clay panels, sd=0,36m Straw insulation (95mm), sd=0,2m Paper based vapour retarder, sd=5m Straw insulation (200mm), sd=0,7m Hunton Windproof, sd=0,42m
1400
Saturation pressure
1200
Vapour pressure
36,7
16,9
1000 800 600
400
400 0
1
2
3
4
5
6
7
8
sd (m)
0
1
2
3
4
5
6
7
sd (m)
EcoCocon
Wood fibre DIFFUSION DIAGRAM The wood fiber insulation is placed within a wooden frame structure, whereas the other layers are the same as for the straw panel wall.
DIFFUSION DIAGRAM A concern for the placement of the building in this case was the experience of nature that is rooted deeply in our design criteria, and here the shape of the building creates a FIG. 61- Two different wall build-ups
POCP
GLOBAL WARMING POTENTIAL (GWP) Global Warming Potential. Expressed as CO2 equivalents and refers to the global warming potential of CO2 emitted into the atmosphere. 1,09E-03
128
DESIGN PROCESS
FIG. 62- Global warming potential of two build-ups
2,60E-05
129
