Key Definitions

Embodied Carbon
The greenhouse gas emissions associated with materials and construction processes throughout the whole life cycle of an asset.
Environmental Product Declaration (EPD)
A third-party verified, standardized document that provides the environmental impact of a product, based on the data from a life cycle assessment.
Greenhouse Gas (GHG) Emissions/Carbon Emissions
Emissions of gasses including carbon dioxide, methane, and water vapor that trap heat in the atmosphere. The global warming potential (GWP) of these gasses is measured in CO2e (carbon dioxide equivalent).
Operational Carbon
The greenhouse gas emissions arising from all energy and water consumed by an asset in use, over its life cycle.
Disaster-Resilient Housing
Housing that provides a safe, locally appropriate, healthy, and secure space. Moreover, it is affordable and a secure financial investment for its occupants. Resilient housing initiatives are sustainable, adaptable, and scalable. For further details on how Build Change defines resilient housing, refer to the Build Change Guide to Resilient Housing.
Equivalent New Construction
A new house with the same structural system and degree of resistance against earthquakes and hurricanes as the retrofit house. The size and architectural details of the house may be different.
Green Housing
The application of green building to housing, where green building is the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building's life-cycle from siting to design, construction, operation, maintenance, renovation and deconstruction.
Housing Deficit
Calculated as the difference between the population’s need for housing and what is available, the housing deficit comprises (1) the “quantitative housing deficit,” which refers to the amount of housing that does not exist or is unusable, compared to the number of families that require housing; and (2) the “qualitative housing deficit,” which refers to the amount of existing housing that is structurally deficient, lacks basic habitability requirements such as access to services (water, sanitation, and electricity), or is otherwise of inadequate quality.
Informal Housing
Housing that has been built outside of the processes recognized by formal construction. For example, it may have been built without the input of a licensed engineer or designer and without a construction permit. Informal housing is used in this guide to refer to the informal process through which the house was constructed. It does not make specific reference or judgment regarding the type of land on which the housing is present, or the ownership of the land or property.
Life Safety
A structural design performance level in which the postevent damage state of a structure has damaged components, but retains a margin against the onset of partial or total collapse. Houses that meet the life safety performance level have been designed or retrofitted to meet the required hazard intensity levels defined by building codes.
Lightweight Roof
A roof composed of timber or light-gauge steel framing, typically pitched, and covered with roof cladding. Layers of additional waterproofing, insulation, or structural sheathing may also be added.
The reinforcement or upgrading of existing structures to make them more resistant and resilient to the damaging effects of hazards.
Risk Reduction
Building improvements that reduce the risk of damage or collapse in the next disaster, but do not target a specific level of performance.
Vertical Expansion
Increasing the floor area of a house by adding another story. Vertical expansion interventions include strengthening of the existing first floor structural elements to safely support an additional story, and (if applicable) converting an existing sloping, lightweight roof into a slab.
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