MBI and BD+C Modular Advantage | Winter 2012
 

Durability, Adaptability & Building 
Service Life Planning
As Applied to Modular Construction

By Dru Meadows
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Dru Meadows, principal with theGreenTeam Inc., is an architect, specifier, author, teacher, and environmentalist with 20+ years experience in sustainability consulting. She is a fellow with the Construction Specifications Institute and with ASTM International. Her work has received recognition from the City of Los Angeles, the state of Oklahoma, the White House, and the United Nations. She is a recognized expert in sustainability standards and has contributed to numerous programs, including development of the International Organization for Standardization (ISO) standards for Service Life for which she chaired the U.S. Technical Advisory Group and served as the American Delegate from 1999 – 2005.

AIA/CES
Learning Objectives

To earn one AIA/CES learning unit, read this article and the test questions, then submit your answers by clicking the Submit Test Answers link at the bottom of this page.

1. Differentiate Building Service Life Planning (BSLP) from Life Cycle Assessment (LCA) in the management of environmental impacts over the life cycle of a building.

2. Distinguish between design life and service life in the development and implementation of BSLP.

3. Explain closed-loop life cycle concepts for building design using relocatable modular building as an example.

4. Identify BSLP requirements in standards and codes such as the International Green Construction Code (IgCC) Public Version 2 and ASHRAE 189.1 Standard for the Design of High-Performance Green Buildings.
 
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Also Available for AIA/CES Credit:
 
 
 
 

Envionmentalists concur that nature is the ideal for sustainability. Nature has a “closed loop” life cycle. Each destructive process supports a new creation. There is no “end-of-life” - only transitions into new beginnings. Nature does not waste. Nature endures and evolves. Nature repurposes and recycles.

Buildings and building products striving for sustainability must examine their full life cycle. Products, for example, may be used momentarily (packaging for transport of construction materials), a few years (carpeting that wears our or becomes aesthetically outdated), or decades (steel framing that remains until remodel or deconstruction). Regardless of the intended service life, eventually all of the materials reach the same point...end-of-life. Then what? If buildings are viewed as stockpiles of future resources, then materials would be reclaimed and recycled over and over again. We may even “mine” old buildings as a matter of course. Even today, old utilitarian wood structures such as barns and mills are carefully disassembled for their fine, tight-grained timbers. Yesterday, such wood was commonplace. Today, it is expensive if you can get it at all. Who knows what future valuables our structures may contain? 

Buildings and building products striving for sustainability need to pattern their life cycles on the life cycles found in nature. They need to be adaptable and/or durable.  They need to anticipate end-of-use and options for reclamation, repurposing, and recycling. And, most importantly, they need a plan to manage their life cycle impacts. The best of intentions are meaningless if there is no implementation.

Building Service Life Planning (BSLP) provides the plan for implementation. Although BSLP utilizes and documents life cycle considerations, it should not be confused with a Life Cycle Assessment (LCA). LCAs evaluate environmental impacts. An LCA is an estimate based upon assumptions regarding the life cycle of a product. It does not provide guidance to help realize the LCA projections. BSLP is similar to the planning and documentation that typically is conducted for any building project. The primary distinction is that BSLP examines the full life cycle of the building and its components.

  • BSLP functions as a design tool. As a design tool, it is similar to life cycle costing (value engineering) techniques that address both environmental and economic objectives. 
  • BSLP captures design decisions that may affect performance quality. As such, it is similar to building program requirements that consider not only construction and use requirements, but also requirements for deconstruction, reuse, and end-of-life.
  • BSLP provides guidance on achieving the design goals for the overall life of the building. As a guidance document, it is similar to an operations and maintenance manual but with clarification of conditions of use and the impacts the conditions may have on durability and adaptability.

Green building programs, rating systems and standards have been relatively silent on this topic. Other than requirements for recycled content and construction waste management, there has been little recognition of closed-loop life cycle techniques. And, there has been virtually no recognition of the environmental benefits of durability. Most of the discussion of end-of-life impacts and durability in environmental circles tends to highlight negative attributes such as the impacts and longevity of toxins and radioactivity. Unfortunately, that has ignored some very important, sustainable attributes. Until recently. Both the International Green Construction Code (IgCC) Public Version 2 and ASHRAE 189.1 Standard for the Design of High-Performance Green Buildings have changed that. Both incorporate BSLP.

IgCC (PV2) – Excerpts from Section 505 Service Life

505.1.1 Core, shell and site hardscape components. The Building Service Life Plan (BSLP) shall be based on the Building Service Life Category (BSLC) selected from Table 505.1.1. The design life of components shall be not less than indicated in Table 505.1.1 for the BSLC selected, except as approved by the code official in cases where practical difficulties are identified in the BSLP. The BSLP shall include a maintenance, repair, and replacement schedule for each component. Values for component design life and the in-use conditions related to maintenance, repair and replacement schedule shall be based on manufacturer’s reference service-life data or other approved sources and shall be included in the documentation.

Table 505.1.1

BUILDING DESIGN LIFE CATEGORIES AND MINIMUM COMPONENT DESIGN LIFE

BUILDING DESIGN LIFE CATEGORY COMPONENT
COMPONENT MINIMUM DESIGN LIFE (Years)
60 Years 25 Years
Structural elements and concealed materials and assemblies 60 25
Materials and assemblies where replacement is
cost prohibitive or impractical
60 25
Major materials and assembles that are replaceable 40 25
Roof Coverings 20 20
Mechanical, electrical and plumbing equipment and systems 25 25
Site hardscape 20 20

 

All building owners engage in some level of BSLP with every decision they make in the purchase and renovation of their building. They probably don’t call it BSLP. But, they do it. They may not engage a consultant or generate a glossy report. But, they do develop conclusions about the how long the building or building component will last (the design life) and what the likely maintenance and repairs will be (the plan) for it to actually last that long (the service life). Every BSLP is different and will depend upon the project objectives and budget. The owner who plans to occupy a building for 20 years, for example, will evaluate initial costs and operating costs differently than the owner who plans to sell the building immediately.

When you weigh the relative costs and benefits of any purchase – an automobile, a computer, a coffee maker – you are considering some variation of the following questions:

  1. What is the initial cost?
  2. How long will it last?
  3. Does it do what I want it to do (if it does more, is that good or unnecessary and expensive)?
  4. Will a new model make it obsolete in a year?
  5. What are the installation or assembly requirements (Do I need a specialist or can I do it myself)?
  6. How reliable is the performance (does Consumer Reports rate this model highly)?
  7. Does anybody provide service for this?  Is help available locally (or do I have to ship it somewhere at my expense)?
  8. Will it cost me more to repair than to replace?
  9. Do I have to be especially careful with it (can it withstand the kids, the dog, etc. easily)?
  10. What are the additional costs (insurance, gas, etc. for the teenager’s new car)?
  11. Will this end up in the attic or garage in a year?
     

ASHRAE 189.1 (2009) Paragraph 10.3.2.3

Service Life Plan. A service life plan that is consistent with the OPR shall be developed to estimate to what extent structural, building envelope (not mechanical and electrical), and hardscape materials will need to be repaired or replaced during the service life of the building. The design service life of the building shall be no less than that determined using table 10.3.2.3. The estimated service life shall be documented for building assemblies, products, and materials that will need to be inspected, repaired, and/or replaced during the service life of the building. Site improvements and hardscape shall also be included. Documentation in the Service Life Plan shall include the building project design service life and basis for determination, and the following for each assembly or component:

a. Building assembly description
b. Materials or products
c. Design or estimated service life, years
d. Maintenance frequency
e. Maintenance access for components with an estimated service life less than the service life of the building

Provide a Service Life Plan at the completion of design development. The owner shall retain a copy of the Service Life Plan for use during the life of building.

TABLE 10.3.2.3 Minimum Design Service Life for Buildings

Category Minimum Service Life Building Types
Temporary          up to 10 years                       Non-permanent construction buildings (sales offices, bunkhouses) Temporary exhibition buildings
Medium life 25 years Industrial buildings Stand-alone parking structures
Long life 50 years All buildings no temporary or medium life, including the parking structures below buildings designed for long life category

 


With every investment, large and small, we perform some level of service life planning.  Buildings are large investments. So, the process tends to be more formalized.  Owners examine initial costs, operating costs and return on investment when considering a building project. They analyze the anticipated costs against benefits of any expenditure.  At a very fundamental level, that is BSLP.


Building Service Life Plan (BSLP)

A BSLP shall demonstrate that the performance requirements are achievable for in-use conditions for duration of the design life.

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design life: The intended lifespan; the service life predicted under the in-use conditions

in-use condition:
A physical characteristic associated with normal use.

service life:
The actual lifespan.

BSLP is generally used for and measured by economic impacts.  How long will a product that costs US$50 per square foot last in comparison to one that costs US$100?  In contrast, Life Cycle Assessment (LCA) is used for and measured by environmental impacts. What are the overall greenhouse gas impacts attributable to the product?  BOTH processes examine the life cycle.  However, BSLP is not just an evaluation; it is a plan. It not only identifies life cycle economic impacts, it helps to manage them.

"Envionmentalists concur that Nature is the ideal for sustainability. Nature has a “closed loop” life cycle. Each destructive process supports a new creation. There is no “end-of-life” - only transitions into new beginnings. Nature does not waste. Nature endures and evolves. Nature repurposes and recycles."

More recently, BSLP has been utilized to help manage life cycle environmental impacts.  By examining the maintenance, repair, and replacement costs for a specified design life, BSLP tends to encourage durability, interoperability, adaptability, reuse and recyclability.  It is viewed environmentally as the antithesis of planned obsolescence. 

It is this application of BSLP – the management of life cycle environmental impacts - that is addressed by ISO standard 15686-6 Buildings and constructed assets - Service life planning - Part 6: Procedures for considering environmental impacts. It is this application of BSLP that is incorporated in the International Green Construction Code (IgCC) Public Version 2 and into the ASHRAE 189.1 Standard for the Design of High-Performance Green Buildings. And, it is this application of BSLP that best supports Whole Building Design.  (Refer to the National Institute of Building Sciences’ Whole Building Design Guide,

Whole Building Design (also called “integrated design”) requires the involvement of all design/construction team members and future users or tenants.  It emphasizes the interconnectedness of disciplines and views the building as a system, rather than a collection of components. The latter perspective limits significantly how sustainable a design can be, as it really only allows for a process of substituting “green” features for conventional ones.  Furthermore, a conventional design process - which tends to encourage the segregation of the disciplines - can result in a fragmented design that may not meet all of the design objectives.  In fact, a lack of coordination can negatively and dramatically affect performance such as energy use and water consumption.  On the other hand, viewing the building as a system allows full integration of decision making.  Not only does this approach get better performance out of a building overall, it is also the best way to avoid unnecessary costs.

BSLP supports the Whole Building Design process.  It aids decision making by providing a common framework for establishing project goals.  It organizes the data collection, evaluation, and reporting for the project.  And, it establishes the basic parameters for successful operation and maintenance to achieve the goals.

Relocatable Modular Building BSLP Case Study



Relocatable modular buildings are utilized for schools, construction site offices, medical clinics, sales centers, and in any application where a relocatable building can meet a short term space need. These buildings offer fast delivery, ease of relocation, low-cost reconfiguration, accelerated depreciation schedules, and enormous flexibility. Relocatable modular buildings are designed and built to be demountable. While they are installed in accordance with applicable code requirements, they are not permanently affixed to the real estate. Commercial modular buildings are non-residential structures that are 60 to 90 percent completed off-site in a controlled environment, with final assembly in the field at the building site.

A relocatable modular building must meet the same quality and function requirements that a site-built structure would be expected to meet. Additionally, a relocatable modular building has some extremely unique performance requirements and, consequently, a unique BSLP.

The performance requirements for a relocatable modular building differ from a site-built structure in 3 major ways. Unlike a site-built structure, a relocatable modular building:

  1. Is not site-specific. Because a relocatable modular building is not site-specific, it is necessarily designed for adaptability. Relocatable modular buildings serve short term and/or urgent needs. A school district, for example, may find itself without the capacity for a rapidly expanding student population. It needs space quickly, but cannot predict which schools will require a long term addition of square footage. So, it leases space. Flexible space. Relocatable modular buildings are designed and built for fleet inventory as equipment rentals. They are designed and built for multiple geographic locations, without knowing where the units will be installed. To accommodate a range of sites and uses, they must comply with the codes and regulations of multiple jurisdictions.
     
  2. Is designed for deconstruction and reuse. Because a relocatable modular building is designed for deconstruction and reuse, the components are standardized and harmonized to facilitate adaptability. The modular units are largely prefabricated – WITHOUT knowing where they will be installed. They are stored until purchased or leased. Then, they are transported and assembled in the field. After they have served the purpose, the modules will be removed and relocated to another site for another use. A relocatable modular building is intentionally designed for disassembly.  And, for reassembly.
     
  3. Is designed for transportation in component modules.  Because a relocatable modular building is designed for transportation in component modules, it has both size and weight limitations. Component (module) size is limited by transportation regulations which vary by state. In general, the maximum width is 14 feet and the maximum height is 14.5 feet unless otherwise mandated by state or federal transportation regulations. Weight also is limited by transportation regulations which vary by state. Additionally, the design must consider vibration, shear and wind loads applicable during transit.

A BSLP is fundamentally a different plan for relocatable modular buildings than for site-built structures because the life cycle of a relocatable modular building is defined purely by its service. It is intended to serve a short term purpose (or, more accurately, a series of short term purposes). At the conclusion of the need, the building is intended to be removed. This contrasts dramatically with site-built structures. 

A site-built structure is rarely, if ever, designed in consideration of end-of-life or with the goal of eventual removal. Even if an owner anticipates a service life of 10-15 years, a relatively brief useful life, he/she doesn’t usually intend for the building to be demolished at that time. Unfortunately, it is all too often anticipated that it will be sold...and become somebody else’s problem. So, the original BSLP is based upon an abbreviated design life and decisions are guided accordingly.  www.wbdg.org/wbdg_approach.php

Establishing a longer perspective for a building design life - regardless of the number of owners during the building’s life - is one of the environmental objectives of a BSLP in green building programs. Requiring an end-of-life perspective is an even greater environmental objective. By planning for maintenance, repair and replacement of building components over an extended period of time, end-of-life must necessarily be addressed.  What do you do with the old carpet when you redecorate? With the old roof when the roof is replaced? What about energy or water conservation upgrades? How do you access the equipment and reconfigure or replace it? The average site-built structure does not have a plan to address these types of impacts. The average relocatable modular building does. It is inherent in the building program because the program is simply service.  Materials are reconfigured, reused, and recycled to serve as needed.

End-of-life is a specific design consideration for relocatable modular buildings. A relocatable modular building is expected to have a design life of about 40 years. Industry studies predict that a relocatable modular building is likely to be relocated an average of 8 times over its life. After that time, the components are commonly repurposed or recycled. There are usually multiple tenants across the service life; there may be multiple owners. 

The modular building industry provides an excellent example of closed-loop life cycle thinking, implemented with a comprehensive BSLP.

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AIA Continuing Education Test

1. Sustainable design for both buildings and building products should target a closed-loop life cycle in order to:

a. Improve energy efficiency
b. Increase durability
c. Meet green building requirements
d. Avoid waste and adapt to changing needs

2. Which of the following describe BSLP

a. Functions as a design tool
b. Captures design decisions that may affect performance quality
c. Provides guidance on achieving the design goals for the overall life of the building
d. All of the above.

3. A Building Service Life Plan can help implement a closed-loop life cycle and:

a. Is the same as a Life Cycle Assessment
b. Varies according to project objectives and budget
c. Measures the design life of a building
d. All of the above

4. Virtually every building project utilizes some level of Building Service Life Planning.
 
A. True
B. False

5. As defined in the International Green Construction Code (IgCC), the “design life” of a building component is:

a. The intended service life
b. The warranty period
c. The life cycle
d. The actual lifespan

6. Both the IgCC and ASHRAE 189.1 Standard for the Design of High-Performance Green Buildings:

a. Require closed-loop life cycle techniques for construction waste management
b. Incorporate BSLP to help manage life cycle environmental impacts
c. Establish a minimum design life of 50 years
d. Establish a minimum design life of 25 years

7. Because a relocatable modular building is not site-specific,

a. It is designed for adaptability 
b. It is constructed primarily in the factory with final assembly in the field
c. It must comply with the codes and regulations of multiple jurisdictions
d. All of the above
 
8. A BSLP is fundamentally a different plan for relocatable modular buildings than for site-built structures because the life cycle of a relocatable modular building

a. Is defined purely by its service
b. Is shorter than for site-built structures
c. Is longer than for site-built structures
d. Must comply with state and federal transportation regulations

9. Establishing a longer perspective for a building design life – regardless of the number of owners during the building’s life – is one of the environmental objectives of a BSLP in green building programs.
 
a. True
b. False

10. A relocatable modular building is designed to accommodate deconstruction and reuse, with an average of:

a. 6 relocations over a 20 year design life
b. 4 relocations over a 40 year design life
c. 8 relocations over a 40 year design life
d. 8 relocations over a 30 year design life


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