In the past few years green building or green construction has become a much examined topic, rejected (in practicality) by many, embraced (in action) by few (most everyone talks “green”, fewer do it). It carries an unnecessary association with “elitism” (but, I can’t claim that this is undeserved, as too many in the business promote an elitist view of green building). Its a media buzz-word, and a rallying cry for reform. It is often promoted by energy efficiency zealots, and back-to-natural proponents as the only way to go – but, few actually adopt green methods and materials as part of the way they build or conduct business.
As Kermit says, “Its not easy being green.”
What is Green Building? And When is a Building “Green”?
A review of what people are saying about their green products, homes and structures will leave you believing that there are many shades and hues of green. I purpose here to claim that there is but a single shade of green, and a business, home or structure is either green or not, striving to be green, or not striving at all.
So what is a “green” building? Lets look at some common definitions of “green building”:
- Green building enhances the natural and human environment
- Green building is sustainable development
- Green building uses existing materials in efficient ways
- Green building is low-energy resource-efficient construction
All construction of any kind is an enhancement (for better or worse depending on your point of view) of its surroundings. Sustainable development is change that does not knowingly impair viable future development – the future value of choices are incorporated into any economic transaction, and building anything is a complex economic transaction. Economic necessity forces builders to use materials (including energy) in efficient ways. All of these broad generalizations do little but direct the effort of design and construction. They do not make a structure “green.” They each lack a base-line for comparison and measurement. Existing definitions quickly expand on these conceptual goals to lay-out some specific criteria for environmental responsibility [hence green construction is, by this admission, an ethical/moral standard of construction, and necessarily an engineering standard], materials and energy efficiency. Principal among definitions are two core themes: (1) energy-efficiency; and, (2) applied “building science” (also called “whole-house design”).
Energy-efficient building construction remains at the core of green building design – since 40% of energy consumption in the US is from heating and cooling structures, it will remain the institutional focus of green construction for many years. Marginal gains in building energy efficiency do have profound long-term impacts on overall energy use and prices in the US. Many of the smart ideas for building green have their origins in the research and development of energy efficient materials and methods of construction. The largest financial payoff to the building owner will come from the energy saving features that are incorporated into the design of a structure. It remains the easiest selling point for building in a green way; but, alone, it will not render a home “green.” Taken to its extreme, energy-efficient construction can lead to a very tight low-energy home, but one that will leave its occupants sick (and that’s not the sort-of green we’re looking for)… as a consequence green construction has come to embrace the concept of building science in order that the various parts of a house can be examined for their integrated impact, not just on energy efficiency, but on many other facets of home construction.
Building science is an approach to construction that considers the totality of the structure, its purpose and its place in the environment. Building science is an application of scientific knowledge focusing on the analysis and control of the physical phenomena affecting buildings; it includes the detailed analysis of building materials and envelope systems. The practical purpose of building science is to provide predictive capability to optimize building performance and understand or prevent building failures. Building failure does not just occur when a structure falls down [although we can learn a lot when it does!]. A building fails when its components break due to stress or fatigue (a structural failure), or, more commonly, when one or more of its purposed performance goals are not being met (i.e., its too hot, or too cold, or too drafty, or too expensive to maintain, etc.). [A great place to enquire about the practical application of building science is: buildingscience.com – a private research firm with a public agenda.]
Energy efficiency is concerned with the thermal properties of the building envelope, and the energy used by the building’s appliances and fixtures. The only performance criteria is active-energy consumption. Building science goes beyond that by considering building performance in several specific categories: component durability; moisture management; energy efficiency; indoor air quality (IAQ); structural performance; and, thermal comfort. Using building science as a tool, one can analyze how various building components and assemblages interact and affect a building’s overall performance, as well as individual performance categories. For example, which side and pane of glass a low-e film is applied to does more than affect the heat load of a room or house, it will affect IAQ as the mechanical system responds to heat and humidity at different times of the day or season; that, in turn affects how well comfort levels are maintained in any part of the house, including the home’s ability to absorb or rid itself of airborne moisture or other contaminants. In other words, all the parts are related, a change in one component can have a large impact in many areas of a home’s design, not just the component’s designed purpose.
Building science applies itself to the structure (the environment inside the building envelope), and only considers the outside environment as uncontrolled phenomena applied to the structure – it has little to say about the built environment in which the structure is situated, or the impact building the structure (and altering the site) will have on the site itself and the community it is in. Building science is an engineering approach – performance goals are legal parameters (set by outside agencies) for structural integrity, materials composition and environmental quality. Building science arrives at the most efficient construction response that meets these pre-set parameters.
Applying the principles of building science to the design and construction of a home will result in a sound, comfortable and safe structure. It doesn’t mean that the methods of construction will be green, or that the end result will be a green home. Green building and green building standards look beyond the building envelopment, and gauge the impact of the building on its surroundings, and the impact its surroundings will have on the occupants of the building.
Following from building science as a multi-faceted and performance based, green building, and, by extension, green standards, are multi-faceted and performance based. An overall designation for the home is arrived at based on the performance of the structure as built (not just designed) in several categories.
NAHB National Green Building Standard
FGBC Green Home Designation Standard
USGBC LEED for Homes
|Categories||Lot Design & Development|
Indoor Environmental Quality
Operations & Maintenance
Points are awarded based the degree to which materials and technologies are employed to achieve the objectives of a performance category. Minimums and prerequisites exist in the various categories – these ‘dictums’ are the collective judgment of standard’s owner on what constitutes ‘green’. Each standard treats the failure meet minimums differently, preferring to use the point system as an incentive structure to adopt increasingly better integrated performance across categories and overall for the house. Meet the minimums in each category, and the minimum overall performance goal for the standard, and home is declared green. Each standard presently, has overall performance tiers or ranks depending on the degree to which a structure exceeds the minimum overall performance level.
Homes/structures are designed and built to meet or exceed acknowledged (and/or binding) structural, mechanical, plumbing, electrical, fire and accessibility standards – because they are binding legal requirements for construction these standards are more properly referred to as building codes. Before a project is considered finished and the structure occupied for its built purpose, designs are reviewed, materials and methods of construction or installation inspected, and the structure verified as complying with its applicable code(s). This inspection and verification is not performed by the architect, nor the builder, nor the homeowner – it is performed by a third-party (usually a local government official or proxy) with no financial interest in the construction of the building.
A certified green structure will have gone through the same process: design, procurement and construction will have been reviewed and inspected against an accepted standard by a disinterested third-party verifier. A structure is “green” not because of its design, or means of procurement, or method of construction. A structure is not “green” because the builder, or realtor, or homeowner says it is. In the same manner that a structure is declared code compliant, a structure is green because it has been declared so by a recognized third-party authority who has verified that the design, materials and means of construction meet specific and accepted criteria for the built environment in which people will abide, work and recreate.
Building codes are accepted and enforced standards of construction. They are, arguably, economically justifiable regulatory interventions in an otherwise voluntary contractual relationship between a builder/designer and a homeowner (ostensibly protecting the principal parties, as well as those parties external to the contract but affected by its execution – e.g., public and private utilities, insurance companies, financial institutions, etc.). The codes are mandated and enforceable. The codes are arrived at through a technically and economically informed, democratic process overseen by publically accountable corporate bodies.There are several published guidelines and standards that fall within the category of “green building.” In the state of Florida there are only three standards that apply to residential home construction which are subject to independent third-party verification.
Green building standards differ radically from regulatory building and development codes. Chief among these differences are:
(1) Green standards are the property of private corporations (albeit not-for-profit entities). The USGBC oversees LEED. The NAHB owns and administers the National Green Building Standard (NGBS). The FGBC controls the various Florida Green Designation Standards.
(2) The standards are voluntary. There is no binding law compelling anyone to build green structures, or to build green. There is no penalty for failing to build green (other than a failure to be certified).
(3) Performance goals are multi-faceted, they do not represent prescriptive engineering minimums. There is a caveat here: all green structures go beyond code minimums (all structures must meet the legal minimums, hence better is good, and good is the goal). All standards contain elements of prerequisite qualities, but there is no set prescriptive means of meeting that prerequisite.
(4) All standards are arrived at through an informed, transparent process. They are not necessarily accountable to the general public, but the process is accountable internally to the organization’s membership. (In the case of the NGBS, the principle entity relied on an independent body to formulate the standard – the ICC published the standard formulated using the ANSI process).
(5) Authority and credibility is obtained through market respect and recognition, and the participation of its membership/clientele. Any one standard’s success depends on its marketing success (internally to its members, and externally through homebuyer demand).
Building green and a Green building are not necessarily the same things.
A green building is not necessarily the consequence of building green; but you have to construct in a green way to build a green structure.
A green building is declared so by an independent third-party after it has been verified against a defined and recognized standard.
There is no greener shade of green, than green; anything else is marketing.
Green building standards are, by admission, ethical/moral judgments concerning what are good/better building practices and good/better built-environment performance goals.
Building green is a response to economic/market forces that is influenced by the ethical/moral character of the builder/contractor. Likewise, the homeowner demand for green buildings is a response to moral imperatives that is influenced by household economics.