Natural Hazards and 

Sustainability for 

Residential Buildings

FEMA P-798 / September 2010

Natural Hazards and 

Sustainability for 

Residential Buildings

FEMA P-798 / September 2010
Authors

David S. Gromala, Consultant, Principal Author 

Omar Kapur, URS Corporation

Vladimir Kochkin, National Association of Home Builders Research Center

Philip Line, URS Corporation, Project Manager

Samantha Passman, URS Corporation

Adam Reeder, PBS&J

Wayne Trusty, Athena Sustainable Materials Institute

Reviewers

Don Allen, Steel Framing Alliance

Wanda Edwards, Institute for Business and Home Safety

Gary Ehrlich, National Association of Home Builders

Simon Foo, Public Works and Government Services Canada

Caroline Frenette, Centre d’expertise sur la construction commerciale en bois (cecobois) 

Claret Heider, National Institute of Building Sciences

Eric Letvin, URS Corporation, Program Manager

Randy Melvin, Winchester Homes

Janice Olshesky, Olshesky Design Group, LLC

Susan Patton, URS Corporation

Kevin Reinertson, California Office of the State Fire Marshal

Mike Rimoldi, Federal Alliance for Safe Homes

Tona Rodriguez-Nikl, Oregon State University

Paul Tertell, FEMA

Frances Yang, ARUP

Acknowledgments

Lee-Ann Lyons, URS Corporation, Layout Designer

Billy Ruppert, URS Corporation, Illustrator
S

ustainable building design concepts are increasingly being incorporated 

into residential building design and construction through green building 

rating systems. While the environmental benefits associated with 

adopting green building practices can be significant, these practices must be 

implemented in a manner that does not compromise the building’s resistance to 

natural hazards, such as high winds, earthquakes, floods, or wildfires.

This document examines current green building rating systems in a broader context. It identifies 

green building practices—the tools of today’s green building rating systems—that are different 

from historical residential building practices and that, unless implemented with an understanding 

of their interactions with the rest of the structure, have the potential to compromise a building’s 

resistance to natural hazard events. This document discusses how to retain or improve natural 

hazard resistance while incorporating these green building practices. While most common 

green building practices provide sustainability advantages with little or no effect on structural 

performance or durability, others require reevaluation of the building’s structural design or detailing 

to retain its integrity during natural hazard events. Often, only minimal design modifications are 

required to maintain natural hazard resistance. 

Understanding interactions between green building practices and natural hazards will benefit 

users—particularly designers, builders, code officials, and those who develop green building rating 

systems, codes, and standards—by providing a perspective that green building practices, while 

important on their own, must be part of a larger context that encompasses life safety, disaster 

resistance, and other related considerations.

Natural Hazards and Sustainability for Residential Buildings ES-1

Executive Summary

Table of Contents

Executive Summary ............................................................................................................................ES-1

Section 1: Introduction.......................................................................................................................... 1-1

Section 2: Green Building Rating Systems, Codes, and Standards .................................................... 2-1

2.1 Defining Green Building Performance Levels .......................................................................... 2-2

2.1.1 Green Building Categories in ICC-700............................................................................ 2-3

2.1.2 Relating Category Provisions to Performance .............................................................. 2-4

2.2 Green Building Rating Systems and the Building Codes .......................................................2-6

Section 3: Sustainable Building Design............................................................................................... 3-1

3.1 Decision Process for Sustainable Building Design ..................................................................3-3

3.2 Added Benefits of Sustainable Building Design .....................................................................3-4

Section 4: Sustainability and Natural Hazards ................................................................................... 4-1

4.1 Seismic Hazard........................................................................................................................... 4-1

4.2 Wind Hazard...............................................................................................................................4-2

4.3 Flood Hazard ..............................................................................................................................4-2

4.4 Wildfire Hazard...........................................................................................................................4-2

4.5 Green Building Practice Natural Hazard Sensitivity Matrix ..................................................4-2

Section 5: Examples of Green Building Practices and Natural Hazard Resistance........................... 5-1

5.1 Example 1: Rooftop Solar Photo-Voltaic Panels........................................................................5-2

5.2 Example 2: Solar Shading Using Roof Overhangs ...................................................................5-4

5.3 Example 3: Elevating a Structure Above the Base Flood Elevation – 

Material Minimization Considerations .................................................................................... 5-7

Appendix A: Sustainability and Life Cycle Assessment.................................................................... A-1

Appendix B: Acronyms..........................................................................................................................B-1

Appendix C: References and Resources ...............................................................................................C-1

Natural Hazards and Sustainability for Residential Buildings i
ii Natural Hazards and Sustainability for Residential Buildings

Table of Contents

List of Figures

Figure 1: Summary of IgCC Regulatory Framework for Residential Construction ............................ 2-2

Figure 2: Green Building Categories of ICC-700..................................................................................2-3

Figure 3: Hazard Resistance Evaluation Process for Green Building Practices.................................3-3

Figure 4: Example 1 – Installing a Roof-Mounted Solar Panel System ..............................................5-2

Figure 5: Example 2 – Large Roof Overhang for Solar Shading ..........................................................5-4

Figure 6: Example 2 – Avoided Environmental Impacts for Two LCA Indicators..............................5-6

Figure 7: Example 3 – House Elevated on Piles in Coastal Flood Zone A ......................................... 5-7

Figure 8: Example 3 – Building Plan....................................................................................................5-8

Figure A1: Humanized Terms for One LCA Indicator for Example 2 House ..................................... A-4

List of Tables

Table 1: Green Building Practice Natural Hazard Sensitivity Matrix ................................................4-3

Table 2: Example 2 – Details for Adding Solar Shading Overhang....................................................5-5

Table 3: Details of Buildings for Example 3 – Building Elevation in Flood Zone...............................5-9

Table 4: Sample National Flood Insurance Program Flood Insurance Premiums for 

Buildings in Zone A and Coastal Zone A..............................................................................5-9

Table A1: LCA Indicators for Example 2 House................................................................................. A-3
Natural Hazards and Sustainability for Residential Buildings 1-1

The purpose of this document is to describe the interactions, both 

positive and negative, between common green building practices and 

the robustness of residential buildings to withstand natural hazards. 

Understanding these interactions will benefit users—particularly designers, 

builders, code officials, and homeowners—by providing a perspective that 

green building practices, while important on their own, must be part of a 

larger sustainable building design context that encompasses life safety, 

disaster resistance, and other related issues. Many hazard resistance issues 

are addressed in model building codes such as the International Residential 

Code (IRC). However, some of the building modifications introduced by green 

building practices create design, detailing, and installation challenges that are 

not covered by the IRC’s provisions. This document identifies specific areas in 

which special attention to a few small details will maintain or increase natural 

hazard resistance.

This document uses the terms “green building practices” and “sustainable building design” in a 

very specific context. The term green building practices commonly refers to products or practices 

implemented to achieve a level of environmental performance above a minimum or traditional 

design. This document focuses on practices that are assigned credit under a green building rating 

system. The term sustainable building design refers to a broader concept that includes not only 

fundamental sustainability principles, but also considers and addresses the risks associated with 

natural hazards. Other significant aspects of sustainability, such as societal issues and ecosystem 

health, are outside the scope of this discussion.

Voluntary green building rating systems are gradually being replaced by mandatory requirements in 

local and State jurisdictions. As mandatory green building requirements become more widespread, 

building designers, code officials, and builders will increasingly be faced with decisions on how to 

comply with applicable building code requirements while implementing the new green building 

SECTION 1

Introduction
practices. As demonstrated later in this document, the implications of green building practices on 

the capability of buildings to resist natural hazards are not always evident. 

The document provides an overview of existing residential green building rating systems in the 

United States (Section 2). It describes a range of common green building practices and their 

interactions with structural performance and durability (Section 3). Section 4 introduces specific 

concerns related to seismic, wind, flood, and wildfire and provides a summary table that ties 

several specific green building practices to design, detailing, and installation considerations to 

enable those practices to be implemented without compromising natural hazard resistance. To 

illustrate the concepts discussed in the document, Section 5 provides three examples:

•	Example 1 illustrates some of the many interactions to be considered when incorporating a 

roof-mounted solar panel system in the home design.

•	Example 2 illustrates that the increased loads associated with large roof overhangs (added for 

solar shading) can be resisted by adding a minimal amount of enhanced connectors into the 

building system. This example demonstrates the environmental benefits of retaining natural 

hazard resistance by quantifying those benefits using life cycle assessment (LCA) techniques 

(the LCA methodology is summarized in Appendix A). 

•	Example 3 illustrates the rapid financial payback for increasing, rather than minimizing, 

foundation framing material when elevating a building in a specific flood zone design case.
Natural Hazards and Sustainability for Residential Buildings 2-1

There are several nationally recognized green building rating systems 

in the U.S. that apply to residential construction. The largest of these 

are the National Green Building Standard (ICC-700 [NAHB, 2008a, 

b]), promulgated jointly by the National Association of Home Builders and 

the International Code Council (ICC), and the “Leadership in Energy and 

Environmental Design (LEED) for Homes” rating system promulgated by U.S. 

Green Building Council (refer to references for Web site). It is anticipated that 

many of the local and regional residential green building programs in use today 

(described by Bowyer, 2010) will eventually convert to one of the national rating 

systems. 

This document primarily uses the provisions of ICC-700 as the basis for examining common 

green building design practices for residential buildings and their interactions with sustainable 

building design for natural hazard resistance. ICC-700 was chosen because it is a nationally 

recognized consensus standard, and is referenced in the current draft of the ICC International 

Green Construction Code (IgCC [ICC, 2010 – publication anticipated in 2011]). It must be noted 

that the use of ICC-700 as the basis for discussion in this document is not intended to indicate a 

preference for ICC-700 relative to either LEED for Homes or any other green building rating system. 

A single reference document was chosen to maximize clarity in the discussions that follow.

The ICC IgCC will provide a new regulatory framework for introducing green building practices 

into the built environment. An outline of this framework specific to residential construction is 

SECTION 2

Green Building Rating 

Systems, Codes, and 

Standards
2-2 Natural Hazards and Sustainability for Residential Buildings

Green Building Rating Systems, Codes, and Standards

depicted in Figure 1. A key element of the IgCC is that it serves as an “overlay” code such that its 

provisions work with, rather than replace, provisions of other model codes that regulate building 

construction. Under this framework, green building practices are clearly understood as being in 

addition to other requirements of the International Codes.

2.1 Defining Green Building Performance Levels

Green building rating systems have various methods for establishing their requirements. Most 

have adopted a multi-tiered approach for defining levels of green performance. For example, 

achieving a specific threshold number of points under ICC-700 enables a building design to achieve 

a performance level of Bronze, Silver, Gold, or Emerald, where Emerald represents the highest 

performance level. Other programs, such as LEED for Homes, use a similar approach. In addition to 

the green performance attributes specifically identified by rating systems, a sustainable building 

design process should address questions (only some of which are covered by this document) related 

to whether the product or building practice degrades any performance attribute relative to the 

product or practice it is replacing; these questions include:

•	Is the design as resilient or robust under extreme events (such as high winds, earthquakes, 

floods, fire)?

•	Is it as durable under both normal and extenuating service conditions (such as high humidity 

or extreme temperatures)?

•	Does it introduce any hidden dangers (such as increased chemical exposure)?

•	Is it more sensitive to quality of installation (and the risks associated with imperfect 

installation)?

Administration and Enforcement

Administrative requirements of the IgCC work in tandem with 

the administrative requirements of other International Codes.

Jurisdictional Requirements

Jurisdiction can: a) require enhanced performance using 

Table 302.1 of the IgCC; and b) establish the environmental 

performance level in accordance with Table 303 of ICC 700.

Baseline Requirements for Residential

Performance levels as described in ICC-700, and minimum 

requirements of the effective building code.

Figure 1: Summary of IgCC Regulatory Framework for Residential Construction
Natural Hazards and Sustainability for Residential Buildings 2-3

Green Building Rating Systems, Codes, and Standards

•	Does it affect the performance, durability, or efficacy of adjacent materials or other portions of 

the structure (such as increasing corrosion rates of materials in contact with it)?

•	Are there other unforeseen consequences of its use (such as changing internal building 

cavity moisture and temperature conditions, potentially leading to condensation and mold)?

Builders and homeowners will also ask two additional (practical) questions to determine whether 

the sustainability benefits of the green product or building practice are significant enough to justify 

its substitution in place of more familiar products or practices:

•	How large are the environmental benefits (quantified by LCA or other measures)?

•	What are the costs of implementation?

2.1.1 Green Building Categories in ICC-700

There are six green building categories included in ICC-700 (refer to Figure 2). Some provisions in 

ICC-700 address specific sustainability goals (e.g., improved energy efficiency garners increased 

rating system points). Other provisions discourage specific practices that negatively affect 

occupant health or the local environment (e.g., not permitting the use of materials with high 

volatile organic compound [VOC] emissions). Still other provisions encourage considering a much 

broader perspective, such as cradle-to-grave impacts (e.g., providing credit for analyses that show 

life cycle benefits). 

Points in each ICC-700 category are summed to arrive at the total number of points credited 

to achieve a performance level. Under this system, different numbers of points are assigned for 

various practices. 

Within ICC-700, the relative balance of minimum number of points required to achieve the Bronze 

Level among the six categories is approximately as follows: lot design – 16 to 17 percent; resource 

efficiency – 19 to 20 percent; indoor environmental quality – 16 to 20 percent; energy efficiency – 13 

to 17 percent; water efficiency – 6 to 8 percent; and operation and maintenance – 2 to 3 percent. In 

Figure 2: Green Building Categories of ICC-700
2-4 Natural Hazards and Sustainability for Residential Buildings

Green Building Rating Systems, Codes, and Standards

Comparison of ICC-700 and LEED for Homes Categories

addition to these minimum points per category, additional points from any category—14 percent 

to 24 percent—must be acquired to meet a specific performance level.

Although this document focuses on the provisions of the ICC-700 rating system, many users will 

evaluate their residential buildings under the LEED for Homes rating system. Its eight evaluation 

categories correspond to the six ICC-700 categories shown in Figure 2 (refer to text box above).

2.1.2 Relating Category Provisions to Performance 

When green building practices are being considered, their effect on the building’s natural hazard 

resistance must be evaluated as part of the building design process. Typically, three areas related 

to the proposed building modification must be examined:

1. Are any design changes required to maintain compliance with code provisions related to 

hazard mitigation specific to the region or to other aspects of structural performance and 

durability?

2. Are there any special building detailing issues that must be addressed?

3. Will any special installation and maintenance instructions need to be developed and 

communicated in the field?

While this document focuses on maintaining structural performance required by code, it is not 

intended to discourage designing to higher natural hazard resistance performance targets. Users 

choosing to invest in green may also choose to concurrently invest in added structural or durability 

performance.

The following discussion provides examples of specific green building practices in each ICC-700 

category that are most likely to affect structural performance and durability. The categories of 

Water Efficiency and Indoor Environmental Quality, which have limited interaction with natural 

hazard resistance, are not included in this discussion. 

ICC-700 Categories Corresponding LEED for Homes Categories

Lot Design, Preparation, and Development

•	 Innovation and Design Process 

•	 Location and Linkages 

•	 Sustainable Sites

Water Efficiency Water Efficiency

Energy Efficiency Energy and Atmosphere

Resource Efficiency Materials and Resources

Indoor Environmental Quality Indoor Environmental Quality

Operation, Maintenance, and 

Building Owner Education Awareness and Education
Natural Hazards and Sustainability for Residential Buildings 2-5

Green Building Rating Systems, Codes, and Standards

Lot Design, Preparation, and Development 

Beneficial interactions: Green building practices that minimize slope disturbance, soil 

disturbance, and erosion can also significantly improve the resistance of a neighborhood to 

some natural hazards (such as earthquakes, some types of flooding, and wildfires). Further, 

development of stormwater management plans, hydrologic analysis and soil studies, and 

other such actions that garner points under ICC-700 can also guide the designer to solutions 

that increase a building’s resistance to natural hazards. 

Special considerations: Site selection decisions that qualify for green rating system points 

should also consider the dominant natural hazards in a region. For example, development of 

an infill site should include consideration of floodplain and stormwater management issues. 

Resource Efficiency 

Beneficial interactions: Green building practices that optimize building framing (per ICC700 Section 601.2) can have a significant effect on structural performance. When this design 

accounts for the dominant natural hazards in a given region, optimization can improve 

structural robustness. For example, optimization in a high-wind region often includes 

reinforcement of highly stressed connections. 

Special considerations: The Commentary to Section 601.2 of ICC-700 encourages 

evaluating advanced framing techniques for wood construction that use less framing 

material in the building while complying with applicable structural requirements. In some 

cases, the optimization of framing creates additional design challenges for designers to 

maintain load paths and other aspects of structural capacity. Unless these techniques are 

carefully implemented, some aspects of the structure may be compromised. For example, 

increasing framing spacing from 16 inches on center (o.c.) to 24 inches o.c. garners credits in 

the ICC-700 rating system, but provides fewer points of connectivity both within walls and 

between the walls and the roof. In this case, proper installation of each connection is more 

important than in a more redundant configuration. 

Energy Efficiency

Beneficial interactions: Green building practices that improve energy efficiency by using 

thermal mass can also increase resistance to certain natural hazards. For example, the use 

of properly detailed concrete or masonry walls can improve resistance to windborne debris in 

high-wind events.

Special considerations: Increasing thermal mass increases the loads imparted on a 

building in an earthquake. The use of heavier walls increases bracing required to withstand 

increased earthquake loads. Additionally, energy efficiency decisions that reduce the 

number or effectiveness of framing connectivity (due to increased framing spacing [see 

previous example under Resource Efficiency] or wider spaces between structural framing 

and sheathing or siding) require special attention to detailing. For example, thick exterior 

insulating sheathing in a high-wind region may require non-standard attachment and 

flashing to maintain resistance to wind suction and wind-driven rain intrusion into wall 

cavities. 
2-6 Natural Hazards and Sustainability for Residential Buildings

Green Building Rating Systems, Codes, and Standards

Operation, Maintenance, and Building Owner Education

Beneficial interactions: ICC-700 provides credit for communicating important building 

operation and maintenance information to the homeowner. This information can help the 

homeowner to maintain critical areas in the exterior building envelope, thus minimizing 

long-term water intrusion and associated building degradation. These simple steps will, in 

the long run, lead to improved wind and seismic resistance for well-maintained buildings. 

2.2 Green Building Rating Systems and the

Building Codes

Green building rating systems assume implementation of green building practices that are in full 

compliance with applicable building codes. ICC-700 specifically states this requirement as follows:

“101.3 Intent. ... This Standard is not intended to abridge safety, health, 

or environmental requirements contained in other applicable laws, codes, 

or ordinances.”

The ICC-700 statement of intent clarifies that green building practices are implemented in addition

to other requirements of the building code. This process is assumed to provide acceptable building 

performance in design level natural hazard events. In some regions in the U.S., detailed local review 

of residential plans is routine. In these areas, building designers will typically apply residential 

building code provisions to new green building practices, thus meeting the intent of ICC-700. In 

other regions of the U.S., the latest building code might not be adopted for residential construction 

and there might be limited structural plan review or inspection. 

A fundamental reason for developing this document is to focus the attention of a designer, builder, 

or homeowner who chooses to modify an existing design (or an existing building) by adding one 

or more green building features in an effort to improve a building’s sustainability. The primary 

message is to consider the effect of the modification on other aspects of the building’s performance. 

The effect of the modification on natural hazard resistance should not be assumed to be accounted 

for by local building department or building designer review or inspection.
Natural Hazards and Sustainability for Residential Buildings 3-1

The concepts of sustainability and green buildings are defined in a variety 

of ways, often depending on the particular organization addressing 

the topic. Consensus based definitions for sustainability and green 

building have been adopted within both national and international standards 

development organizations. The term sustainability has been defined as:

Sustainability “The maintenance of the ecosystem components and 

functions for future generations” (American Society for Testing and 

Materials [ASTM] E 2432)

Sustainable development “Development that meets the needs of the present without 

compromising the ability of future generations to meet their own needs” (ASTM E 2432)

When sustainability focuses specifically on buildings, the term “green building” is often used and 

has been defined as:

Green building “A holistic approach to design, construction, and demolition that 

minimizes the building’s impact on the environment, the occupants, and the community” 

(CALGreen, 2010) 

Green building “A building that meets the specified building performance requirements 

while minimizing disturbance to and improving the functioning of local, regional, and global 

ecosystems, both during and after its construction and specified service life” (ASTM E 2432)

As used in today’s green building rating systems, the concepts of sustainability and green building 

are generally limited to specifically defined attributes. For instance, although the definitions of 

both sustainability and green building include implicit consideration of building longevity, building 

SECTION 3

Sustainable Building 

Design
3-2 Natural Hazards and Sustainability for Residential Buildings

Sustainable Building Design

longevity is not explicitly included in the definitions for either concept. Further, the implementation 

of individual green building practices is often characterized by a practice-by-practice approach 

(for example, a focus solely on energy efficiency) or a focus on material use in terms of a single 

attribute, such as recycled content. 

Broader considerations for residential building construction—including life-safety protection and 

limiting property damage during natural hazard events—are assumed to be adequately addressed 

by building code requirements and are generally not addressed in today’s green building rating 

systems. Even broader environmental implications, such as global warming effects, ozone depletion, 

and the release of toxins to air, land, and water, are often only indirectly addressed. 

As discussed in Section 2, the IgCC will further clarify what Section 101.3 of ICC-700 already 

requires—that green building practices must be implemented in a coordinated manner that 

considers a broad range of other performance requirements. The concepts in this document are 

intended to provoke discussion to connect green building rating systems with a broader definition 

of sustainable building design that includes building longevity and natural hazard resistance. The 

National Institute of Building Sciences (NIBS) Whole Building Design Guide (WBDG) program 

states that, “While the definition of sustainable design is constantly changing, six fundamental 

principles persist” (NIBS, 2010). Those principles correspond directly with the six green building 

categories in ICC-700 shown in Figure 2. The WBDG expands the discussion by identifying two 

related issues, building resiliency and building adaptability, as follows:

“Building resiliency is the capacity of a building to continue to function and operate under 

extreme conditions, such as (but not limited to) extreme temperatures, sea level rise, natural 

disasters, etc. As the built environment faces the impending effects of global climate change, 

building owners, designers, and builders can design facilities to optimize building resiliency.”

“Building adaptability is the capacity of a building to be used for multiple uses and in 

multiple ways over the life of the building. For example, designing a building with movable 

walls/partitions allow for different users to change the space. Additionally, using sustainable 

design allows for a building to adapt to different environments and conditions.”

In this context, building resiliency is closely aligned with natural hazard resistance. The additional 

concept of building adaptability is more relevant in nonresidential structures and will not be 

addressed further in this document. On this basis, a broad definition that includes both green 

building practices and hazard resistance concepts could be: 

Sustainable building design Building design that addresses fundamental sustainability 

principles by optimizing the use of land, materials, energy, and water for human occupancy 

and ecosystem health while considering the ability of the building to resist natural hazards.
Natural Hazards and Sustainability for Residential Buildings 3-3

Sustainable Building Design

3.1 Decision Process for Sustainable Building Design

The decision process for implementing a new green building practice must consider several 

factors based on the specific technique and its intended function in accordance with minimum 

requirements of the building code. Figure 3 is a flowchart of a process to evaluate the interaction of 

green building products and practices with natural hazard resistance. Although the basic approach 

of the flowchart can be applied to any new building technique that could affect the integrity of the 

building structure, it is intended to be specific to green buildings.

Figure 3: Hazard Resistance Evaluation Process for Green Building Practices
3-4 Natural Hazards and Sustainability for Residential Buildings

Sustainable Building Design

It is important for builders and homeowners 

to remember that some decisions that add 

green features to a residence may affect the 

structural performance or natural hazard 

resistance of the building. These interactions 

are not always readily apparent (refer to 

Sections 4 and 5 for specific examples).

Another important factor in successfully 

implementing a green building practice is 

the availability of detailed manufacturer’s 

installation instructions, maintenance 

procedures, and contractor adherence to 

minimum requirements and product use 

limitations described in the manufacturer’s 

instructions and product literature. History 

has shown that for a broad range of building 

products and practices (not specific to green 

building) failure to follow manufacturer 

instructions and maintenance procedures 

has been demonstrated to result in failures in 

high-wind events. 

3.2 Added Benefits of Sustainable Building Design 

Designing buildings so that they both resist natural hazards and provide environmental benefits 

has distinct advantages to homeowners, their neighbors, and society in general. For example, 

every home that survives a hurricane:

•	Provides post-disaster shelter for the home’s occupants

•	Minimizes windborne debris to downwind homes

•	Removes the need for one additional temporary housing structure

•	Provides post-disaster sustainability benefits (less material to landfill, less new material 

needed for reconstruction)

If a home includes additional features, such as zero energy use or other self-sufficiency attributes, 

it can provide “passive survivability” as well. Passive survivability is the capability of a building to 

provide adequate shelter for its occupants to survive within the building for several post-disaster 

days without reliance on outside infrastructure. A checklist of specific design techniques that 

improve the passive survivability characteristics of a building is available (Environmental Building 

News, 2006). Passive survivability is also discussed on the NIBS WBDG Web site (NIBS, 2010). 

Mitigation Assessment Teams

Federal Emergency Management Agency 

(FEMA) has deployed Mitigation Assessment 

Teams (MATs) after major natural disasters for 

the past 25 years to collect data and present 

findings detailing how and why buildings have 

failed from natural hazards. MAT reports have 

historically found that construction often does 

not meet the level of performance targeted 

by model building codes. For instance, there 

was widespread damage to residences from 

Hurricane Ike even though wind speeds were 

less than the mapped design level wind speeds. 

FEMA P-757, Hurricane Ike in Texas and Louisiana 

(FEMA, 2009), reports that residential buildings 

without adequate elevation, proper construction, 

and proper foundation selection were found to 

have widespread failures. Successful building 

design and construction practices are detailed 

in Chapter 9 of FEMA 549, Hurricane Katrina in 

the Gulf Coast (FEMA, 2006), which describes 

building design and construction practices that 

can minimize damage even in an extreme event 

such as Hurricane Katrina.
Natural Hazards and Sustainability for Residential Buildings 4-1

SECTION 4

Sustainability and 

Natural Hazards

Most common green building practices provide sustainability 

advantages with little or no effect on structural performance or 

durability of the building. Other practices can affect the structural 

performance, sometimes in subtle ways. Still other practices can significantly 

change the structure’s response and require reevaluation of the structural design 

or detailing to retain the building’s integrity under extreme events. A summary 

description of green building practice interactions with seismic, wind, flood 

and wildfire natural hazards is provided below, followed by a matrix (Table 1) 

showing specific green practices that can affect natural hazard resistance.

4.1 Seismic Hazard

Typical light-frame residential buildings resist seismic forces through a system of horizontal 

diaphragms and vertical shear walls. The individual components rely on continuity of perimeter 

framing, inter-component connections, and anchorage to an adequate foundation to resist these 

forces. Green building practices that increase the weight of the structure will increase the seismic 

forces. Practices that interrupt the continuity of perimeter framing members, reduce the strength of 

the members, or reduce the strength of anchorages and inter-component connections can decrease 

the seismic resistance of the building. These load path and detailing issues should be addressed 

by the building designer when applying building code provisions related to seismic design. 
4-2 Natural Hazards and Sustainability for Residential Buildings

Sustainability and Natural Hazards

4.2 Wind Hazard

Many high-wind events are characterized by a combination of wind and rain. Even minor breaches 

in the building envelope can result in significant water intrusion and economic loss. Light-frame 

buildings require roof-to-wall connections capable of resisting wind forces. Many portions of a 

building experience high suction forces in a high-wind event that can lead to sheathing or siding 

“blow off.” As with resistance to seismic forces, buildings resist lateral wind forces through a 

system of horizontal diaphragms and vertical shear walls interconnecting building elements into 

a continuous load path that is critical for successful performance. Green building practices that 

decrease the redundancy of framing and therefore decrease surfaces for connection between 

sheathing and framing elements can potentially increase the likelihood of localized connection 

failures. Practices that increase the building’s wind profile will increase the wind forces 

experienced by the building. Practices that attach equipment or vegetation to exterior surfaces 

have the potential to increase windborne debris. These load path and detailing issues should be 

addressed by the building designer when applying building code provisions related to high-wind 

design. 

4.3 Flood Hazard

The only flood-related design consideration addressed in this document is building elevation. 

Green building practices that encourage reductions in framing materials can also be interpreted 

to encourage building to code-minimum elevations. This practice can increase the likelihood of 

flood damage when compared to elevating a residence to greater than building code minimums. 

4.4 Wildfire Hazard

Green building practices that encourage vegetation for shading and wildlife corridors in the 

defensible space surrounding the building have the potential to make the building more vulnerable 

to damage from the spread of fire. The concept of defensible space is typically addressed explicitly 

by local jurisdictions in regions subject to urban-wildland interface codes. The properties of 

materials used on the building envelope and their layout also greatly influence the performance of 

a building in a wildfire event.

4.5 Green Building Practice Natural Hazard 

Sensitivity Matrix 

Table 1 (Green Building Practice Natural Hazard Sensitivity Matrix) highlights the potential 

interactions, both positive and negative, between specific green building practices and one or 

more natural hazards (wind, seismic, flood, and wildfire). Each row entry includes a brief descriptor 

of the green building practice, a graphical representation of that practice, a characterization of 

the interaction with each natural hazard, and a summary explanation of the potential interaction 

along with suggested techniques to resolve the issue. “Interaction” means that the specific green 
Natural Hazards and Sustainability for Residential Buildings 4-3

Table 1: Green Building Practice Natural Hazard Sensitivity Matrix

Sustainability and Natural Hazards

building practice has the potential to influence resistance to the hazard specified. The summary 

explanation of the potential interaction or alternative techniques consists of general statements 

intended to encourage thought and further consideration of improved techniques of design, 

detailing, and/or installation. 

Example green building practices shown in Table 1 are applicable to comparable provisions in 

LEED for Homes. ICC-700 Section

Description of 

Green Building 

Practice Graphical Depiction

Natural Hazards

SeismicFloodWindWildfireExplanation of Relationship

Lot Design, Preparation, and Development

501.1 (1)

Lot: An infill 

lot—vacant or 

underutilized land 

with pre-existing 

utilities—

is selected. NA NA

This credit incentivizes building on 

vacant or unutilized land that has at 

least some existing utilities on the 

property. 

Flood: Infill development within flood 

hazard areas increases flood risks. 

Check items such as foundation type, 

elevation, and materials for compliance 

with flood-resistant construction 

practices.

Wildfire: Maintain perimeter 

protections against wildfires.

503.2

Slope 

disturbance: All 

or a percentage 

of development 

on steep slopes is 

avoided.

Development away from steep slopes 

reduces risks from seismic, wind, 

wildfire, and flood hazards.

Slope 

disturbance:

Hydrological/soil 

stability study for 

steep slopes is 

completed and 

used.

NA NA

Consideration of hazards associated 

with steep slopes and their 

hydrological/soil stability will identify 

potential slope sliding issues due to 

an earthquake or potential for flooding 

and erosion damage. The study can 

recommend appropriate siting or 

mitigation techniques.

NOTE:

 indicates relationship between the green building practice and the given natural hazard that should be considered.

“NA” indicates little or no significant relationship between the green building practice and the given natural hazard.
4-4 Natural Hazards and Sustainability for Residential Buildings

Table 1: Green Building Practice Natural Hazard Sensitivity Matrix (continued)

Sustainability and Natural Hazards ICC-700 Section

Description of 

Green Building 

Practice Graphical Depiction

Natural Hazards

SeismicFloodWindWildfireExplanation of Relationship

Lot Design, Preparation, and Development

503.4 (3)

Stormwater 

management:

Impervious 

surfaces that do 

not absorb water 

are minimized, and 

permeable surfaces 

are used.

NA NA NA

A greater amount of pervious surface 

improves stormwater management for 

small-scale flooding events at the site. 

Pervious surfaces can: 

•	 Minimize flooding 

•	 Protect groundwater supplies 

•	 Reduce contamination issues from 

surface water

503.4 (4)

Stormwater 

management: A 

roof that is partially 

or completely 

covered with 

vegetation (a green 

roof) is installed on 

the building.

NA

Additional dead load, potential debris, 

and durability factors create additional 

considerations for green roofs. 

For dead load considerations, the 

structure should be evaluated for its 

ability to resist the added roof weight. 

The roof waterproofing system should 

be evaluated for its ability to resist 

leaks, root penetration, and moisture 

related problems.

Seismic: Evaluate structure’s ability to 

resist increased seismic forces from 

increased roof weight.

Wind: Evaluate system’s ability to 

minimize potential for the roof surface 

to become windborne debris.

Wildfire: Vegetation on a building 

can increase the building’s risk from 

wildfires.

Resource Efficiency (material usage, advanced framing techniques)

601.2

Increased framing 

spacing: Increase 

wood or steel stud 

spacing to reduce 

material usage and 

increase insulation. 

May include 

increased spacing 

of floor and roof 

framing.

NA NA

Using 24-inch stud spacing (as 

opposed to 16-inch stud spacing) 

results in each stud carrying a greater 

load, reduction in number of studs for 

connections, and increased spans for 

sheathing and other finish materials.

Seismic and Wind: Check the design 

capacity of the studs, stud attachment 

to plates, fastener schedule, sheathing 

thickness, and load path for outof-plane wind and seismic loads. 

Increasing stud spacing may affect 

the performance of certain exterior 

finishes under out-of-plane wind 

loads. More fasteners or thicker finish 

materials may be required.

NOTE:

 indicates relationship between the green building practice and the given natural hazard that should be considered.

“NA” indicates little or no significant relationship between the green building practice and the given natural hazard.
Natural Hazards and Sustainability for Residential Buildings 4-5

Sustainability and Natural Hazards

ICC-700 Section

Description of 

Green Building 

Practice Graphical Depiction

Natural Hazards

SeismicFloodWindWildfireExplanation of Relationship

601.2

Two-stud corner:

Frame building 

corners with two 

studs to reduce 

material usage and 

increase insulation 

(wood detail shown, 

also applicable to 

steel).

NA NA

Evaluate design of two-stud corner (as 

opposed to the traditional method of 

three studs) for ability to resist gravity, 

uplift, and overturning loads.

Seismic and Wind: Check details 

for interconnection of wall studs. 

Check hold-down details for shear 

wall overturning as it may be based 

on three-stud corner detail instead of 

two-stud corner.

Single top plate:

Frame connections 

at top of wall studs 

using single wood 

top plate. NA NA

A single top plate (as opposed to 

the traditional double top plate) has 

reduced ability to transfer gravity 

loads and is not effective in acting as 

a diaphragm chord unless properly 

spliced. Check the design of the top 

plate for loads from the framing above.

Seismic and Wind: Check splices for 

continuity.

Right-sized 

header: Design 

wood or steel 

framing for single 

member header 

optimally sized for 

loads. NA NA

A single member header (as opposed 

to the traditional two-member header) 

has reduced ability to transfer 

gravity loads and out-of-plane wind 

loads if not properly designed and 

interconnected. Check the design of 

the header for loads from the framing 

above.

Seismic and Wind: Check connection 

of header to framing for connections to 

transfer out-of-plane wind or seismic 

loads.

Resource Efficiency (other)

604.1

Recycled content: 

Building materials 

with recycled 

content are used 

for minor and/or 

major components 

of the building.

Evaluate the product to ensure that 

it retains the appropriate properties 

for the application, as well as for 

compatibility with the other building 

materials. Evaluate materials for any 

VOCs toxic to human health.

Table 1: Green Building Practice Natural Hazard Sensitivity Matrix (continued)

NOTE:

 indicates relationship between the green building practice and the given natural hazard that should be considered.

“NA” indicates little or no significant relationship between the green building practice and the given natural hazard.
4-6 Natural Hazards and Sustainability for Residential Buildings

Table 1: Green Building Practice Natural Hazard Sensitivity Matrix (continued)

NOTE:

 indicates relationship between the green building practice and the given natural hazard that should be considered.

“NA” indicates little or no significant relationship between the green building practice and the given natural hazard.

Sustainability and Natural Hazards ICC-700 Section

Description of 

Green Building 

Practice Graphical Depiction

Natural Hazards

SeismicFloodWindWildfireExplanation of Relationship

Energy Efficiency

703.1

Building envelope:

Increase exterior 

insulation on 

exterior walls; often 

accomplished 

by use of foam 

sheathing.

NA

Designing for increased insulation 

can change the structural and fire 

properties of the wall.

Seismic and Wind: Check for 

adequate structural strength and 

connections to resist in-plane and outof-plane forces as applicable. Check 

flashing/installation details to address 

potential for water intrusion.

Wildfire: Check siding and sheathing 

used on exterior walls to ensure that 

they have been approved for use in 

wildfire-prone areas.

704.3.1.1 (7)

Solar space 

heating and 

cooling:

Overhangs, 

adjustable 

canopies, awnings, 

or other coverings 

to provide shading 

over glazing.

NA

Extended overhangs require an 

adequate load path and proper 

connections. Check headers and other 

framing members supporting the roof 

for adequate size for the increased 

loads due to the roof itself as well as 

snow load.

Seismic: Check for adequate 

attachment of the roof diaphragm to 

the wall below, as well as the seismic 

load path for increased forces due to 

the weight of the roof and potentially 

increased snow loads.

Wind: Check roof uplift connections, 

soffit details, shear transfer, and sizing 

of roof framing for added loads.

Wildfire: Check requirements for 

protection of soffit vents, fire rating of 

soffit sheathing and coverings, and 

other requirements for protecting the 

underside of the overhang from blown 

embers.
Natural Hazards and Sustainability for Residential Buildings 4-7

Table 1: Green Building Practice Natural Hazard Sensitivity Matrix (continued)

NOTE:

 indicates relationship between the green building practice and the given natural hazard that should be considered.

“NA” indicates little or no significant relationship between the green building practice and the given natural hazard.

Sustainability and Natural Hazards

ICC-700 Section

Description of 

Green Building 

Practice Graphical Depiction

Natural Hazards

SeismicFloodWindWildfireExplanation of Relationship

704.3.1.3 (1)

Solar space 

heating and 

cooling: Vegetative 

or other forms of 

shading around the 

building perimeter.

NA NA

Wind: Trellises, awnings, covered 

porches, and other forms of shading 

that are not designed to resist highwind forces can become windborne 

debris and damage the building. 

Check connections of any structures 

attached to the building or anchored 

nearby.

Wildfire: Vegetative and other 

flammable shading can present a 

wildfire hazard around homes in 

wildfire-prone areas. Ensure that 

vegetation separation is adequate in 

wildfire regions.

704.3.3

Additional 

renewable energy 

options: Roofmounted solar 

photovoltaic panels 

(not applicable to 

building-integrated 

photovoltaic 

systems).

NA

Adding a rooftop solar panel system 

can add dead loads and create 

durability issues. Check the framing 

for adequacy to support the added 

weight of these systems and determine 

if the potential for water intrusion at 

the connections is addressed. The 

designer should also:

Seismic and Wind: Check framing 

and connections for ability to maintain 

load path and resist applied forces.

Wildfire: Check that the flame spread 

rating of the solar panel system meets 

applicable code requirements.

703.1.1

Insulation and air 

sealing: Stagger 

studs within a 

wall for additional 

insulation and 

thermal efficiency.

NA NA

A staggered stud wall provides 

designers with improved sound 

transmission performance. It has 

also been suggested as a technique 

to provide greater cavity space for 

insulation while effectively eliminating 

thermal bridging.

Seismic and Wind: Check structural 

interactions between wall surfaces as 

well as the load path for gravity, uplift, 

and lateral loads. Alternative tested 

assemblies are available that provide 

improved sound transmission and 

thermal breaks.

Natural Hazards and Sustainability for Residential Buildings 5-1

I

t is important to evaluate whether a green building practice will affect a 

building’s integrity or durability in a way that is not obvious or considered. 

The following examples demonstrate how some green practices can affect 

a building’s resistance to natural hazards. The examples are purposely onedimensional and simplistic for two reasons. First, the examples focus on a 

single performance aspect to illustrate a specific potential design consideration 

or oversight. Second, to quantify the consequences of applying a green building 

practice without full consideration of natural hazard resistance, the examples 

use engineering terms or LCA terms that may be unfamiliar to some readers. 

LCA is a methodology for assessing the environmental performance of a 

product, an assembly, or an entire building over its full life cycle, often referred 

to as cradle-to-grave or cradle-to-cradle analysis (refer to Appendix A for more 

information).

The first example lists the considerations that accompany a homeowner’s decision to improve 

energy efficiency by installing rooftop solar panels. The second example compares the minimal 

changes needed to modify a building design to add solar shading (via extended roof overhangs) 

with the benefits (quantified in LCA terms) of natural hazard resistance. The third example 

computes the financial benefits of raising a home several feet above base flood elevation (BFE) 

even though more material would be required.

SECTION 5

Examples of Green 

Building Practices and 

Natural Hazard Resistance
5-2 Natural Hazards and Sustainability for Residential Buildings

Examples of Green Building Practices and Natural Hazard Resistance

5.1 Example 1: Rooftop Solar Photo-Voltaic Panels

Example 1 is intended to demonstrate the steps required when adding rooftop solar panels to an 

existing building to account for hazard resistance. Depending on the mounting detailing, the solar 

panel system could add significant uplift loads to the roof and possibly trigger localized structural 

failure. To retain structural capacity of the roof under high-wind loads, the additional loads of the 

solar panel system must be properly accounted for in the design. The loads must be transferred to 

the roof framing and the complete load path must be evaluated. Although this example focuses 

on solar photovoltaic panels, the structural considerations apply equally to solar hot water panel 

systems. 

Overview of Example 1 

A homeowner decides to add a rooftop solar panel system to an 

existing home (refer to Figure 4).

Figure 4:

Example 1 – Installing a Roof-Mounted Solar Panel System
Natural Hazards and Sustainability for Residential Buildings 5-3

Examples of Green Building Practices and Natural Hazard Resistance

Discussion of Example 1

Numerous additional design and detailing considerations may be needed to properly implement 

the solar panel system, including: 

•	Reviewing applicable requirements of the local building code including, but not limited to, 

requirements for: 

› wind and seismic (e.g., attachments must be properly designed and detailed to resist 

wind and seismic forces)

› wildfire (e.g., fire class rating of the solar panel system must meet local code 

requirements) 

› installation of electrical wiring, including provisions for drilling of holes for wiring in 

structural roof framing members

•	Following manufacturer’s installation instructions to determine: 

› allowable wind pressure rating (the allowable wind pressure rating should exceed the 

design wind pressure rating for the wind speed zone, height, and exposure of the roof)

› applicable conditions for use of the solar panels (including location of the roof relative to 

coastal, salt water, or other corrosive locations and roof conditions such as roof covering 

type and age, roof pitch, and framing system)

› applicable requirements for use of special membranes and sealants and/or use of flashing 

to prevent moisture intrusion 

› methods recommended for maintaining and cleaning the solar panel system

•	Where approved prescriptive solutions are not available, consulting a professional engineer 

where assistance is needed to determine:

› adequacy of the roof framing and attachment method for resistance to wind and seismic 

forces

› presence of a complete load path through the roof, into the wall framing, and to the 

foundation

› the ability of the roof and supporting framing to safely carry the added weight of the solar 

panel system 

•	Checking with the local utility for any local requirements related to on-site electrical power 

generation.

•	Determining what power generation is achievable and matching that to the more important 

electrical loads. It is often not practical to power all electrical loads in a home (e.g., ovens, 

stoves, and air conditioning units), but loads for lights, fuel-fired heating units, refrigerators, 

freezers, and well pumps can typically be powered. Sizing the system to supply these loads 

will help a homeowner respond to natural hazard events (such as ice storms, hurricanes, or 

floods) that can interrupt utility power for extended periods of time. 
5-4 Natural Hazards and Sustainability for Residential Buildings

Examples of Green Building Practices and Natural Hazard Resistance

5.2 Example 2: Solar Shading Using Roof Overhangs

Example 2 is intended to provide an idealized illustration of the effect of increased roof overhang 

length on wind uplift forces. The illustration demonstrates that this green building practice can 

be implemented in a manner that retains the building’s integrity under high-wind loads at little 

additional cost. The consequence of not accounting for the increased uplift forces is presented in 

LCA terms. 

Overview of Example 2 

A building designer is modifying a set of house plans in order to gain points 

to qualify for the next rating system level. The designer decides to extend the 

overhangs of an existing home design to provide solar shading. The initial 

design with an overhang length of 6 inches was code-compliant and prescriptive 

solutions for anchoring to supporting walls were within the scope of the IRC (ICC, 

2009). The designer specifies a larger overhang length of 3 feet, 3 inches (see 

Figure 5).

Figure 5:

Example 2 – Large Roof Overhang for Solar Shading
Natural Hazards and Sustainability for Residential Buildings 5-5

Examples of Green Building Practices and Natural Hazard Resistance

Discussion of Example 2

This example quantifies only the interaction between the increased overhang length and the 

associated increased uplift loads on the roof-to-wall connection. The sustainability benefits of the 

added solar shading are dependent upon the building’s location, orientation, and configuration and 

are outside the scope of this discussion. As shown in Table 2, when compared with the baseline 

roof uplift connector requirement (the originally designed 6-inch overhang), the increased overhang 

length results in nearly 40 percent higher wind uplift forces. While these higher loads are significant, 

they are within a range that can be addressed by reinforcing the roof-to-wall connection. For this 

specific design case, no additional load path redesign is required. Soffit reinforcing may also be 

required to address wind-driven rain intrusion, but a detailed discussion of that requirement is 

beyond the scope of this example. 

Table 2: Example 2 – Details for Adding Solar Shading Overhang

Design Feature Case A: Benchmark building

Case B: Add solar shading and codecompliant structural reinforcement for 

wind uplift

Building size Single story, 41 feet wide x 68 feet long (roof truss span varies)

Wind zone Exposure C, 110 mph design wind speed per American Society of Civil Engineers (ASCE) 7-10

Roof overhang 6 inches 3 feet, 3 inches

Roof uplift 

connector 

force* 

283 pounds 410 pounds

Uplift 

connector**

Proprietary metal strap attached to stud and 

rafter with (8) 10d common wire nails per 

strap

Proprietary metal strap attached to stud and 

rafter with (12) 10d common wire nails per 

strap

* Based on 24-foot truss span.

** Total additional steel required < 3 pounds.

Life Cycle Assessment Implications

The concept of LCA can be applied to residential construction by evaluating assemblies (e.g., 

roof assemblies) or whole buildings to quantify the relative environmental impacts of loss of the 

assembly or the building as a result of a natural disaster event versus the environmental costs of 

improving the initial construction to avoid such losses. The goal of LCA is to cast the net wide 

and capture all of the relevant effects associated with a product or process over its full life cycle. 

Section 609 of ICC-700 provides incentives for LCA.

From an LCA perspective, the environmental cost of adding less than 3 pounds of steel in the 

reinforced connections is negligible. However, it is interesting to hypothesize what would happen 

if these connections were not reinforced when the length of the overhangs was increased. While 

such a scenario is not code-compliant, such oversights are possible especially in regions where 

code enforcement is less stringent or where the building designer is not aware of the design 

modification.
5-6 Natural Hazards and Sustainability for Residential Buildings

Examples of Green Building Practices and Natural Hazard Resistance

In this hypothetical scenario, reinforcing the roof-to-wall connection increases the likelihood that 

the building will withstand high-wind events (such as hurricanes or tornadoes). In LCA terminology, 

attention to this detail has sustainability benefits that are called “avoided environmental impacts.” 

In other words, LCA can quantify the environmental benefits of avoiding a premature failure in 

which the building might experience partial (loss of roof) or complete (loss of entire building) 

structural failure.

The avoided environmental impacts illustrated in Example 2 are computed by standard LCA 

techniques. The results are provided for two scenarios: one in which the roof must be replaced and 

a second in which (possibly due to extensive water damage or broader structural failure) the entire 

building must be replaced. Figure 6 illustrates the avoided environmental impacts for two of the 

primary indicators—primary energy consumption and global warming potential. The results for 

all six primary LCA indicators related to Example 2 are summarized in Appendix A. 

Figure 6:

Example 2 – Avoided Environmental Impacts for Two LCA Indicators
Natural Hazards and Sustainability for Residential Buildings 5-7

Examples of Green Building Practices and Natural Hazard Resistance

Overview of Example 3 

An environmentally minded builder wishes to minimize foundation material in a 

specific home design (see Figures 7 and 8). The home will be located in a coastal 

flood zone. The builder contemplates whether to establish the building elevation 

at the minimum code-prescribed elevation or whether it might be advantageous 

to raise it above that level.

Figure 7:

Example 3 – House Elevated on Piles in Coastal Flood Zone A

5.3 Example 3: Elevating a Structure Above the 

Base Flood Elevation – Material Minimization 

Considerations 

Example 3 is intended to illustrate, in an idealized example, the interaction of framing optimization 

with flood damage risk. It shows that, in some cases, using more framing material rather than less 

is the optimal decision. For this example, insurance premium amounts are used as the indicator 

of flood damage risk.
5-8 Natural Hazards and Sustainability for Residential Buildings

Examples of Green Building Practices and Natural Hazard Resistance

Figure 8:

Example 3 – Building Plan

Discussion of Example 3

There are numerous design and detailing considerations associated with elevating a building to 

various heights. These include, but are not limited to: 

•	Consideration of increased dead load for foundation design and calculation of seismic forces

•	Consideration of increased pile length when sizing the pile to resist wind, seismic, gravity, 

and flood forces

•	Consideration of increased forces on the building from wind

This example shows the differences in flood insurance premiums (which correlate to probabilities 

of damage and/or building failure) versus the material costs of increasing the building elevation 

from the BFE in Case A to 4 feet above BFE in Case B (Table 3). The pile diameter, along with 

the height, was adjusted from Case A to Case B assuming equal moment demand/capacity ratio 

of the piles between the two cases. As shown in Table 3, the material and construction cost of 

increasing the elevation by 4 feet is $5,025.
Natural Hazards and Sustainability for Residential Buildings 5-9

Examples of Green Building Practices and Natural Hazard Resistance

Table 3: Details of Buildings for Example 3 – Building Elevation in Flood Zone

Design Feature

Case A.

Benchmark building

Case B.

Increase elevation by 4 feet

Building size Single story: 28 feet x 40 feet / Pile foundation: 30 piles

Coastal Flood Zone Coastal Zone A 

Height above BFE 0 feet 4 feet

Top diameter of pile 8 inches 11 inches

Volume of foundation 

material per pile 4.5 cubic feet 11.2 cubic feet

Weight of foundation 

material per pile 165.7 pounds 410.2 pounds

Material cost per pile* $112.50 $280.00

Installed cost per pile** $262.50 $430.00

Total foundation cost $7,875.00 $12,900.00

Difference in cost $5,025

* Assume $25.00 per cubic foot. 

** Assume $10.00 per driven foot installation cost (15 feet embedment).

Break-Even Analysis

The annual insurance premium of Case A would be $1,512, while the annual insurance premium 

for Case B would be $526, The difference in cost to elevate the building 4 feet (Case B) is $5,025, 

while the annual insurance premium savings for a $250,000 building (and $100,000 contents value) 

is $986 annually (refer to Table 4). Therefore, homeowners choosing to elevate their home 4 feet 

above the BFE would break even on their investment in 5.1 years.

This example indicates that the increase in initial material cost is overshadowed over time by the 

savings (both financial and in terms of avoided environmental impacts) garnered by elevating the 

building above code-minimum levels.

Table 4: Sample National Flood Insurance Program Flood Insurance Premiums for Buildings in 

Zone A and Coastal Zone A

Floor Elevation above BFE Reduction in Annual Flood Premium Annual Premium* Savings

1 foot 44% $ 850 $ 662

2 feet 59% $ 616 $ 896

3 feet 65% $ 526 $ 986

4 feet 65% $ 526 $ 986

*Coverage: $250,000 Building/$100,000 Contents. 

Rates as of October 2009 per http://www.floodsmart.gov.

Natural Hazards and Sustainability for Residential Buildings A-1

Appendix A:

Sustainability and Life 

Cycle Assessment

Overview

International standards related to sustainability often address the topic in terms of three pillars—

environmental, social, and economic. As discussed in Section 2.1, there are many factors that can 

contribute to a specific product or practice being considered as green. Ideally, the full environmental 

effect of a green practice should be accounted for when addressing the environmental pillar. This 

can be done through the use of LCA. 

Put simply, LCA is a methodology for assessing the environmental performance of a product, an 

assembly, or an entire building over its full life cycle, often referred to as cradle-to-grave or cradleto-cradle analysis. Section 609 of ICC-700 provides incentives for LCA. The concept of LCA can 

be applied to residential construction by evaluating assemblies (e.g., roof assemblies) or whole 

buildings to quantify the relative environmental impacts of loss of the assembly or the building 

as a result of a natural disaster event versus the environmental costs of improving the initial 

construction to avoid such losses. 

In LCA, environmental impacts are generally measured in terms of a wide range of potential 

indicators, such as the following:

•	Fossil fuel depletion

•	Use of other non-renewable resource

•	Water use

•	Global warming potential

•	Stratospheric ozone depletion

•	Ground-level ozone (smog) creation 

•	Nutrification/eutrophication of water bodies

•	Acidification and acid deposition (dry and wet)
A-2 Natural Hazards and Sustainability for Residential Buildings

Appendix A: Sustainability and Life Cycle Assessment

All of these are measures of the environmental loadings that can result from the manufacture, use, 

and disposal of a product. The goal of LCA is to cast the net wide and capture all of the relevant 

effects associated with a product or process over its full life cycle. These indicators do not address 

the human or ecosystem health effects, which is a much more difficult and uncertain task.

In LCA, the indicators associated with making, transporting, using, and disposing of products are 

referred to as embodied effects, where the word embodied refers to attribution or allocation in 

an accounting sense. In the building community, the tendency is to refer primarily to embodied 

energy, but there is a wide range of embodied effects, as per the list of indicators. All extractions 

from the earth and releases to nature are embodied effects. There are also embodied effects 

associated with producing and transporting energy itself (termed pre-combustion effects). 

LCA is already in widespread use around the world, especially for products or systems for which 

the analytical boundaries are well-defined. For example, the LCA impacts can be reasonably 

approximated for materials such as wood, steel, and concrete and for consumer goods such as 

electronic equipment. LCA is also being applied to building assemblies and whole buildings, 

with specialized calculation tools available in various countries. For example, the ATHENA®

EcoCalculator for assemblies and the ATHENA® Impact Estimator for buildings are tools 

in widespread use by designers throughout North America (Athena Institute, 2010a, b). The 

EcoCalculator is directly referenced in the Green Globes (Green Building Initiative, 2010) and 

LEED rating systems for commercial construction. LCA is also being applied by industry, using 

LCA-practitioner tools such as SimaPro and GaBi (PE International, 2010 and PRé Consultants, 

2010), to better understand and improve environmental performance at the manufacturing level. 

The U.S. Environmental Protection Agency (EPA) lists these and other LCA tools and resources on 

its Web site (EPA, 2010). 

Life Cycle Assessment for Example 2 House

A hypothetical house was used to compute LCA parameters to support Example 2 in Section 5.2, 

the solar shading roof overhang example. LCA indicators were computed for the entire house and 

separately for the roof only. Details of the house and a summary of LCA indicators are provided 

below.

Goal: Quantify the LCA avoided environmental impact implications of survival versus failure 

of a building or component. “Loss / Replacement of Whole House” is shown as a worst case 

scenario. “Loss / Replacement of Roof Only” (complete roof separation from the building) 

provides an additional point of evaluation. 

Scope: The analysis is based on building materials (manufacturing, construction, end-oflife transportation) for the Case A scenario, the building as originally designed with 6-inch 

overhangs. (The difference in LCA indicators when including the longer overhangs and 

additional nails outlined for the Case B scenario is negligible.) Operating energy for the house 

is not included in this analysis.
Natural Hazards and Sustainability for Residential Buildings A-3

Appendix A: Sustainability and Life Cycle Assessment

House Details: 

•	Single-story residence on concrete slab floor

•	2,153 square feet (41 feet by 68 feet)

•	Conventional wood-framing with engineered wood truss roof

•	Stucco exterior wall finish; asphalt shingle roofing

LCA Indicators: As shown in Table A1, most of the LCA environmental impacts associated 

with damage to the whole house and damage to the roof relate to the manufacturing of the 

materials, which accounts for over 90 percent of each of the indicators.

Impact Measures Total Units

Percent of Total

Manufacturing Construction

End-of-Life 

Transportation*

Replacement of Whole House

Primary Energy 

Consumption 590,442.69 MJ 93.98% 5.11% 0.91%

Weighted Resource Use 171,127.54 kg 99.55% 0.45% 0.00%

Global Warming Potential 41,106.32 kg CO2 eq 96.93% 3.04% 0.03%

Acidification Potential 17,496.30 moles of H+ eq 96.93% 3.05% 0.02%

Human Health Respiratory 

Effects Potential 162.70 kg PM2.5 eq 99.15% 0.85% 0.00%

Eutrophication Potential 10.30 kg N eq 96.91% 3.06% 0.03%

Ozone Depletion Potential 0.00 kg CFC-11 eq — — —

Smog Potential 123.56 kg NOx eq 93.23% 6.71% 0.06%

Replacement of Roof Only

Primary Energy 

Consumption 187,633.90 MJ 94.74% 4.91% 0.35%

Weighted Resource Use 36,923.36 kg 98.57% 1.42% 0.00%

Global Warming Potential 7,852.49 kg CO2 eq 91.99% 8.00% 0.02%

Acidification Potential 3,470.03 moles of H+ eq 92.76% 7.23% 0.01%

Human Health Respiratory 

Effects Potential 41.61 kg PM2.5 eq 97.54% 2.46% 0.00%

Eutrophication Potential 2.17 kg N eq 97.52% 2.46% 0.02%

Ozone Depletion Potential 0.00 kg CFC-11 eq — — —

Smog Potential 21.33 kg NOx eq 94.05% 5.91% 0.04%

Table A1: LCA Indicators for Example 2 House

* Includes transportation to landfill for materials that are not currently reused or recycled.

Unit abbreviations: kg kilograms

kg CO2 eq kilograms carbon dioxide equivalent

 kg N eq kilograms nitrogen equivalent

 kg NOx eq kilograms nitrogen oxide equivalent

 kg PM2.5 eq kilograms particulate matter (< 2.5μm)

 kg CFC-11 eq kilograms trichlorofluoromethane equivalent

 MJ megajoules

 moles of H+ eq moles of hydrogen equivalent
A-4 Natural Hazards and Sustainability for Residential Buildings

Appendix A: Sustainability and Life Cycle Assessment

Discussion of LCA Indicators: Because LCA indicators are displayed in scientific units that 

are somewhat difficult to put into perspective, it is common to translate these units into socalled “humanized terms” as shown in Figure A1.

Figure A1: Humanized Terms for One LCA Indicator for Example 2 House
Natural Hazards and Sustainability for Residential Buildings B-1

Appendix B: 

Acronyms

ASCE American Society of Civil Engineers

ASTM American Society for Testing and Materials

BFE base flood elevation

EPA Environmental Protection Agency

FEMA Federal Emergency Management Agency 

ICC International Code Council

IgCC International Green Construction Code 

IRC International Residential Code 

LCA life cycle assessment

LEED Leadership in Energy and Environmental Design

MAT Mitigation Assessment Team

NIBS National Institute of Building Sciences

o.c. on center

VOC volatile organic compound

WBDG Whole Building Design Guide

Natural Hazards and Sustainability for Residential Buildings C-1

Appendix C: 

References and Resources

References

American Society of Civil Engineers (2010). Minimum Design Loads for Buildings and Other 

Structures. ASCE 7-10, Washington, D.C.

American Society for Testing and Materials (2005). Standard Guide for General Principles of 

Sustainability Relative to Buildings. ASTM E 2432. 

Athena Institute (2010a). Eco-Calculator. http://www.athenasmi.org/tools/ecoCalculator. 

Athena Institute (2010b). Impact Estimator for Buildings. http://www.athenasmi.org/tools/

impactEstimator.

Bowyer, Jim L. (2010). Green Building and Implications for Wood Markets, Wood Design Focus. 

Vol. 20, No. 1, pp. 3-7. Forest Products Society, Madison, WI. http://www.forestprod.org.

CALGreen (2010). California Green Building Standards Code. California Building Standards 

Commission. http://www.bsc.ca.gov.

Environmental Building News (May 1, 2006). http://www.buildinggreen.com/auth/article.

cfm/2006/5/3/Passive-Survivability-A-New-Design-Criterion-for-Buildings/?checklist=1. 

Date accessed August 31, 2010.

Environmental Protection Agency (2010). Life Cycle Assessment. http://www.epa.gov/research/

NRMRL/lcaccess/resources.html#Software.

Federal Emergency Management Agency (FEMA) (2006). Hurricane Katrina in the Gulf Coast.

FEMA 549.

FEMA (2009). Hurricane Ike in Texas and Louisiana. FEMA P-757.

Green Building Initiative. Green Building Assessment Protocol for Commercial Buildings, ANSI/

GBI 01-2010. http://www.thegbi.com. Date accessed September 2010.
C-2 Natural Hazards and Sustainability for Residential Buildings

Appendix C: References and Resources

International Code Council (2010). International Green Construction Code Public Version 1.0.

http://www.iccsafe.org. Date accessed September 2010. Anticipated that final version will 

be published in 2011.

National Association of Home Builders (NAHB) (2008a). National Green Building Standard.

ICC-700. Washington, D.C.

NAHB (2008b). National Green Building Standard Commentary. ICC-700 Commentary. 

Washington, D.C.

National Institute of Building Sciences (NIBS) (2010). Whole Building Design Guide. 

http://www.wbdg.org/design/sustainable.php. Date accessed July 27, 2010.

PE International (2010). GaBi Software Product Sustainability. http://www.gabi-software.com.

PRé Consultants (2010). SimaPro LCA Software. http://www.pre.nl/simapro. 

U.S. Green Building Council. Green Home Guide. http://greenhomeguide.com/program/

leed-for-homes. Date accessed September 2010.

Wilson, A. (2006). Passive Survivability: A New Design Priority for the 21st Century. GreenSource 

Magazine, June 2006. http://greensource.construction.com/people/0606mag-opinions.asp.

Resources

FEMA (2006). Homebuilders’ Guide to Earthquake-Resistant Design and Construction. FEMA 232. 

http://www.fema.gov/library/viewRecord.do?id=2103.

FEMA (2008). Home Builder’s Guide to Construction in Wildfire Zones. FEMA P-737. http://www.

fema.gov/library/viewRecord.do?id=3646. 

Scientific Applications International Corporation (SAIC) (2006). Life Cycle Assessment: Principles 

and Practice. Reston, VA. http://www.epa.gov/nrmrl/lcaccess/pdfs/600r06060.pdf. 

Unger, N.; P. Beigl; and G. Wassermann (2004). General Requirements for LCA Software Tools.

http://www.iemss.org/iemss2004/pdf/infotech/ungegene.pdf.
Comments/Questions: 

This is the first edition of Natural Hazards and Sustainability for 

Residential Buildings. Please e-mail any feedback or suggestions 

you may have regarding the content, format, or methodology of the 

document to FEMA-Buildingsciencehelp@dhs.gov or call our office 

hotline at 866-927-2104. Comments are encouraged and will be 

considered in the development of future editions.
FEMA P-798

Catalog No. 10250-1