Bio-Based Materials for the Italian Construction …
243
3 Bio-Based Materials for Insulation: The Building
Envelope as a Carbon Sponge
Considering the increasing social emphasis on environmental issues, waste disposal
and the depletion of raw materials, bio-based materials constitute a promising alternative to those obtained from fossil carbon. Fast-growing biogenic materials, e.g.
straw or hemp shives, are highly promising alternatives for insulation, since their
thermal conductivity is generally low, and they can be locally available (Garas et al.
2009). Moreover, the use of by-products of the food industry, like straw in particular,
is highly beneficial from an environmental prospective, since it can be considered as
a by-product of the food industry. Thus, no land competition issues are expected if
straw is largely used as construction material in replacement of conventional nonbiogenic materials. Actually, straw can be considered mostly as a waste, since only
7% of the total production is sold as product—mainly as animal litter—and its use in
construction is a valuable contribute which allows to close the cycle and decrease the
production intensity of construction materials and the depletion of virgin resources
(Eurostat 2017).
During their growth, biogenic materials uptake carbon dioxide through photosynthesis, with a percentage that generally can be assumed as 50% of the dry mass.
Contrarily to timber, which takes longer to be fully regenerated in the forest after
harvesting, straw requires much less time to be regenerated since after just some
months, the vegetal mass harvested can be fully regenerated in the cropland. This
fast regeneration leads to a higher regenerative capacity since the biogenic CO 2 that
will be released after the EoL of the building will be fully compensated by the CO 2
absorbed in the crop (Levasseur et al. 2012; Guest et al. 2013).
It is estimated that up to 150 Mt of CO 2 can be stored in existing facades in Italy
(Ballarini et al. 2014). Thus, building facades can be seen as Carbon Capture and
Storage (CCS) systems when the carbon is effectively massively stored in biogenic
products (structural elements, but especially insulation) and fast captured in crops.
This CCS system, if largely used in construction, can give a significant contribution
to mitigate climate change and achieve the Paris Agreement objectives.
3.1 Evaluation of Carbon Uptake Benefits Through
a Dynamic Life Cycle Assessment (DLCA)
In the next decades, a large share of residential buildings in the EU-28 is expected to
be renovated, and a large amount of insulation materials will be produced. But, when
the primary energy requirements of the buildings are reduced after retrofitting, the
contribution to carbon emissions due the production of insulation materials increases.
The objective of this study, developed together with the chair of Sustainable Construction of ETH Zurich, was to assess the contribution to climate change mitigation
of carbon storage potential in different biogenic insulation alternatives when used
243
3 Bio-Based Materials for Insulation: The Building
Envelope as a Carbon Sponge
Considering the increasing social emphasis on environmental issues, waste disposal
and the depletion of raw materials, bio-based materials constitute a promising alternative to those obtained from fossil carbon. Fast-growing biogenic materials, e.g.
straw or hemp shives, are highly promising alternatives for insulation, since their
thermal conductivity is generally low, and they can be locally available (Garas et al.
2009). Moreover, the use of by-products of the food industry, like straw in particular,
is highly beneficial from an environmental prospective, since it can be considered as
a by-product of the food industry. Thus, no land competition issues are expected if
straw is largely used as construction material in replacement of conventional nonbiogenic materials. Actually, straw can be considered mostly as a waste, since only
7% of the total production is sold as product—mainly as animal litter—and its use in
construction is a valuable contribute which allows to close the cycle and decrease the
production intensity of construction materials and the depletion of virgin resources
(Eurostat 2017).
During their growth, biogenic materials uptake carbon dioxide through photosynthesis, with a percentage that generally can be assumed as 50% of the dry mass.
Contrarily to timber, which takes longer to be fully regenerated in the forest after
harvesting, straw requires much less time to be regenerated since after just some
months, the vegetal mass harvested can be fully regenerated in the cropland. This
fast regeneration leads to a higher regenerative capacity since the biogenic CO 2 that
will be released after the EoL of the building will be fully compensated by the CO 2
absorbed in the crop (Levasseur et al. 2012; Guest et al. 2013).
It is estimated that up to 150 Mt of CO 2 can be stored in existing facades in Italy
(Ballarini et al. 2014). Thus, building facades can be seen as Carbon Capture and
Storage (CCS) systems when the carbon is effectively massively stored in biogenic
products (structural elements, but especially insulation) and fast captured in crops.
This CCS system, if largely used in construction, can give a significant contribution
to mitigate climate change and achieve the Paris Agreement objectives.
3.1 Evaluation of Carbon Uptake Benefits Through
a Dynamic Life Cycle Assessment (DLCA)
In the next decades, a large share of residential buildings in the EU-28 is expected to
be renovated, and a large amount of insulation materials will be produced. But, when
the primary energy requirements of the buildings are reduced after retrofitting, the
contribution to carbon emissions due the production of insulation materials increases.
The objective of this study, developed together with the chair of Sustainable Construction of ETH Zurich, was to assess the contribution to climate change mitigation
of carbon storage potential in different biogenic insulation alternatives when used