Hi Brilliant People:
I'm hoping you can help me with a quick research question. A local colleague is trying to make the case to replace an existing old slate roof with slate vs. "slate look" asphalt shingles on a local public historic building. The bids are 6X higher for slate over the alternative 25-30 year solutions. They understand the longevity and look advantage but the cost is still a major factor. They want to make the sustainability/embodied energy argument. Is there a 3rd party LCA available that compares the two products? Other arguments? Thanks.
- There is an industry average EPD for stone cladding which includes slate but if you look into it is dominated by limestone (60% of the data).
- If you want to get into the weeds you could use the Life Cycle Inventory to calculate environmental impacts for yourselves. The simplist would be to convert the energy consumption in Table 1 into GWP.
- Here is an EPD from Finland specifically for slate. Germany, Ireland, and Spain all have relevant EPDs too.
In my experience it is difficult to make the upfront embodied carbon arguement against asphalt shingles especially when you're looking at c.2-5kgCO2e/m2. So I would definitely consider the fact that slate could last 100+ years. Also depending on how End of Life impacts are calculated these can be high for bitumen products. Other arguements off the top of my head for real slate could be:- no contamination of rainwater run off
- improved durability
- supporting culturally important craft
- moving away from petrochemical products as an acceptable building material
Hope this helps