5.5 Why Improving an Existing House Before a Disaster in the Philippines Saves More Embodied Carbon Emissions Than Waiting Until After the Disaster

LocationLuzon and Visayas, Philippines
ContextPost-disaster, prevention
Number of Houses Analyzed48 retrofit, 2 new construction
HazardsWind, earthquake
Building Type1 story, concrete block masonry with lightweight or reinforced concrete slab roof
Intervention ScopeRetrofit, some with vertical expansion to add a second story
Performance LevelLife safety, risk reduction

Program Details

Build Change has been supporting post-disaster reconstruction in the Philippines following Typhoon Haiyan (known locally as Yolanda) in 2013. However, since 2016 the majority of its programs have been focused on disaster prevention. In contrast to Build Change’s other global programs, the funding model for home improvements in the Philippines predominantly uses private sector finance—loans taken by homeowners from micro-finance institutions (MFIs)—in addition to philanthropic giving, rather than public funding.

Build Change currently has partnerships with four MFIs to offer home strengthening loans, which provide homeowners with the necessary technical as well as financial support to strengthen their home against hurricanes and earthquakes. Most of the houses analyzed for this study were either part of the loan pilot program or commercial customers of the loan.

The houses are typically single-story, with concrete block masonry walls—either unreinforced, or only partially reinforced and/or confined. The improvement interventions are divided into packages that homeowners can implement incrementally, allowing them to split costs over multiple loans to avoid long loan terms and high interest payments.



Before and after: Homeowner Josefina Hagosojos’s house was part of a home improvement intervention in The Philippines


Overall, home improvement programs in the Philippines save 60 percent of the emissions of equivalent new construction. On average, improving existing homes saves 14 metric tons of carbon dioxide per house (0.35 tons per square meter).

Emissions are lower for risk reduction and preventative strengthening projects, and highest when projects are carried out post-disaster and include vertical expansion. The variety of project types in the Philippines program offers an interesting comparison of the impact on carbon emissions. As expected, the intervention type with the lowest emissions are projects that are carried out preventatively and target a risk reduction performance level. Strengthening to life safety performance level increases emissions from 27 percent to 35 percent of equivalent new construction when carried out preventatively before a disaster, and to 42 percent of equivalent new construction when performed post-disaster.

Figure 19: Home Improvement Interventions with Equivalent New Construction in the Philippines

Although vertical expansion considerably increases the emissions of the intervention, the savings are still comparable to strengthening only interventions. For houses with vertical expansion as well as strengthening, the average emissions are 0.44 tCO2e/m²—more than double the emissions of a house with strengthening only (0.19 tCO2e/m²). However, when compared to their respective new construction baselines, the average emissions savings from both types of intervention are the same.[1] The opportunity to safely expand their home and earn additional income from retail or rental space is often a major incentive for homeowners to strengthen their homes, particularly in space-constrained areas of metro Manila.

Figure 20: Home Improvement Emissions by Intervention Type in the Philippines


  1. Average emissions savings of homes with strengthening only: 0.35 tCO2e/m²; emissions savings of homes with strengthening and vertical expansion: 0.35 tCO2e/m².
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