Buildings contribute significantly to environmental impacts such as energy usage, CO2 emissions, and waste generation. Retrofitting existing buildings can reduce these impacts compared to demolishing and rebuilding. Case studies show that retrofitting reduces embodied energy by 22-85% versus new construction. When enhancing disaster resilience, approaches that minimize additional materials and maximize existing structure are most sustainable. Estimating environmental impacts of hazard damage and repairs helps evaluate resilience solutions.

1. Why Buildings?
40%
Building operations alone contribute over 40%
of the energy usage of the United States.
Energy use of country
38%
Building operations alone contribute over 38%
of the CO2 generation of the United States.
CO2 generation of the country
35%
Waste from demolition, construction
and remodeling makes up more than 35% of all
the non-industrial waste of the US.
Non-industrial waste generation
Construction and operation
of buildings have a main
contribution to the
environmental impact
40%
Construction and remodeling of buildings
account for 40% of raw material use of the US.
Raw material usage
(Hartke, 2020; Traykova & Chardakova, 2014)

2. Life Cycle Assessment
Construction
Embodied Energy – The energy used directly or
indirectly in raw material acquisition, production
and the assemblage. Accounts for 20% of whole
energy consumed during life cycle.
Operation
Aging of the building provokes an increase of the
environmental impact
Repair
Done to minimize the environmental impact due to
aging. But repairs are environmentally costly by
themselves.
Demolition
Due to the energy needed for the process and the
wasted materials
(Traykova & Chardakova, 2014)

3. Construction
Operation End of design life/
damaged
Options for aged/ damaged buildings
Demolish the old structure a
rebuild a new structure
Demolish and rebuild
.
Abandon
Strengthen the old structure
and increase the building life
Sustainable retrofitting
Enhance the resilience
Enhance the resilience for expected
disasters at the initial stage and
avoiding the damage

4. Sustainable Retrofitting
Refurbishment of an existing building that aims to reduce environmental impact of that building
• The retrofitting process itself may have a significant
environmental impact
• But sustainable results can be achieved by,
1. Extension of the remaining life time of the
building that results in environmental cost for
the demolition of the old building and the
construction of a new one.
2. Reduction of operational impact
(Traykova & Chardakova, 2014)

5. Special considerations for sustainable retrofitting
01 Adaptive reuse and
adaptation
• Minimizing consumption of energy
• Reusing of existing materials
• Avoiding negative environmental
impacts
• Reduction of construction waste
• Reusing existing sites
02 New construction
technologies
• Modular construction
• Automation with human touch
• Pre tensioning/ post tensioning
• Sustainable design approaches
03 New construction
materials
• Lightweight concrete
• Composite wraps/ carbon fibre jackets
• Epoxy
• Ultra-High Performance Fibre
Reinforced Concrete

6. Case Study
40 years old two storied house in southern Europe
Existing Structure (E)
• 40 years old
• Gross floor area of 164.4 m2
• Two floors
• Reinforced concrete structure
• Double layer hollow brick
walls
• Stone- cement foundation
• Ceramic tile roof with no
insulation
• Wooden parquet floor
finishes
Demolish and rebuild (N)
• Design life of 50 years
• Reinforced concrete structure
• External cavity walls
• VIROC panels roof
Retrofitting (R)
• Another 50 years life
expectation
• Interior, roof and stairs
replaced.
(Gaspar & Santos, 2015)

7. Case study continued..
• Difference between initial embodied
energy of the two scenarios is
significant. This difference accounts for
the energy disposal of demolished
parts and excess new materials.
• About 22% of energy saving is
achieved by retrofitting over building a
new structure
• Retrofitting is a more sustainable option
(Gaspar & Santos, 2015)

8. Case Study
Three storied house in Schaarbeek, Brussels
(Wastiels et al., 2016)
Three options are analysed for the case
study incorporating insulation options
BB - The building is insulated from the inside.
The ground floor is kept uninsulated.
ET - The building is insulated by use of an ETICS
NC –the original building is demolished and a
new building is erected within the same volume.
The complete building is insulated.

9. Case study continued..
(Wastiels et al., 2016)
Impacts on the environment are analysed by ReCiPe methodology and the consideration of individual impact
categories according to the 7 CEN indicators
• Highest environmental impact is given by new construction scenario. A significance higher amount can be
identify in the production phase which includes the demolition.
• New construction scenario has the highest impacts for all categories

10. Case Study
52 years old multi-storied housing block in Austria
(Mørck et al., 2017)
• Retrofitting a structure alone is a environmental friendly
option since it reduces the incorporated initial
embodied energy
• But if sustainable approaches uses in retrofitting,
operational energy demand also can be reduced.
• In this study 85% of the annual energy demand is
reduced by following a sustainable retrofitting approach

11. Disaster Resilience of Buildings
The ability to reduce the magnitude and/or duration of disruptive events. The effectiveness of a
resilient infrastructure or enterprise depends upon its ability to anticipate, absorb, adapt to, and/or
rapidly recover from a potentially disruptive event (NIAC 2009).
Why
Disaster
Resilience
of
Buildings
is
important

12. Disaster Resilience and Sustainability
To increase the
disaster
resilience
Strengthen the
structure
More
materials
More initial
embodied
energy
Sustainability
Green roof at
the top level
High mass
concentration at
the top
High seismic load
attraction at the top
Not Desirable
(Lemay, 2015)

13. Disaster Resilience and Sustainability
How
?
Disaster
Debris
Demolition
Renovation
New structure
• High energy disposal
of waste
• High embodied
energy of new
materials
• High operational
energy

14. Estimation of Environmental Impact
Damage
model
Hazard
curves
Hazard
Fragility
curves
Structure
Estimation of
consequences
(CSHub, 2020)

15. Case Study
Reinforced concrete building against seismic hazard
(Wei et al., 2016)
Properties of normal and enhanced buildings
CO2 emissions for different repair measures
Probability of seismic events Expected no of damaged building over
40 years design period
Expected CO2 emission over design life

16. Case Study
8 storied apartment building in L’Aquila against seismic hazard
(Bari et al., 2020)
Reference building Diagrid enhanced
building
Shear wall enhanced
building
Seismic characteristics
Future considerations

17. Case study continued..
(Bari et al., 2020)
High environmental impact due to demolitions and
re-building

18. Case Study
One story residential building in Florida against flood hazard
(Matthews et al., 2016)
Floor plan of the building
Construction material for typical and flood resistant (according
to FEMA guidance) designs