Our Third Skin: The Building Envelope

Our human skins serve a critical role in how our bodies interface with the external environment. It serves as a crucial barrier to would-be microbial invaders and other nasty pathogens, while retaining water, regulating body temperature, and providing the sense of touch – through which we perceive the world. Needless to say, it’s quite important and well worth protecting – a message

“In a way, the buildings in which we choose to live our lives are very much a kind of  “third skin” and are of critical importance to our health and wellbeing.’ — Lloyd Lee

the skincare industry has studiously capitalized. The market for skincare and anti-aging products is set to hit 114 billion dollars by 2015.

On top of our precious skin we place another layer of protection, comfort, and quite often, personal expression – our clothes. This protective layer forms another layer of added, and adaptable protection. When it’s hot, we put on breathable clothing that will encourage natural ventilation. When it’s cold, we put on thick, well-insulated coats that trap body heat lost through the skin. When it’s sunny, we put on a hat, or a visor, or sunglasses. When it’s raining, we use an umbrella. We wear what we need, when we need to. In many ways, the sheer variety and variation of situation-specific clothing options from which we can choose for any given situation makes apparel more adaptable than our natural-born skins. In many ways, it is our skin – a kind of second skin. Needless to say, it’s quite important and well worth investing in – a message the fashion industry hasn’t hesitated to capitalize on. The U.S. apparel market, the largest in the world, is valued at 331 billion dollars.

In comparison, the entirety of the green building sector, which includes some 2 million green jobs, barely broke 100 billion dollars in 2013. Yet, without question, the buildings we work in, play in, and live in are of equal if not greater importance than the clothes we buy, or what moisturizer we use. The Environmental Protection Agency (EPA) estimates that the average American spends in excess of 90 percent of their time indoors. And while we may wear our skins a hundred percent of the time, the fact remains that maintaining comfortable and healthy indoor environmental conditions ought to be a pressing concern. In a way, the buildings in which we choose to live our lives are very much a kind of  “third skin” and are of critical importance to our health and wellbeing.

Green Skin Care

The building envelope, which effectively encompasses the whole wall assembly, the roof, windows, doors, and even the floor, is what separates what’s outside from the microcosm of a comfortable home. To that effect, a “good” building envelope, or skin, will minimize the fluctuating effects of the latter while regulating a comfortable, healthy interior space fit for habitation in line with the former.

More importantly, a “good” building envelope is very much a “green” envelope. While much ado has been made about the conflation of energy performance with green terminology in recent times, the truth remains: employing green building practices results in a better-built, higher-quality, healthier, and more energy-efficient building. Why? Because green builders pay exquisite attention to how a home’s envelope functions (or doesn’t), and how those aspects of the building envelope interface, and moderate, the exterior environment.

The quality of a home’s skin can be measured through a variety of means, although typically, these measures relate to the energy efficiency of a building’s envelope. One of the most popular and effective ways of gauging the condition of your home’s skin is through an “energy audit”. Usually performed by trained and licensed professionals from the eco-building sector, an energy audit can help homeowners assess how much energy their house consumes, and evaluate measures to improve efficiency.

Professional auditors typically employ blower door and ductblaster tests to locate areas of air infiltration/exfiltration or leakage in the HVAC system ductwork. A properly insulated home can use 30 to 50 percent less energy than an uninsulated home of a similar size and shape. Additionally, the typical 10-15yr old home loses up to 25% of its cooled and heated air through leaky ductwork in the attic.

Of course, the walls themselves only comprise one aspect of a building’s structural skin. Windows, doors, and other openings too need attention, and sometimes, the discerning eye of a professional. Thirty percent of our energy dollars are lost through windows alone. Double and triple-paned glazing solutions can cut that number down considerably.

Likewise, conventional roofing practices leave much to be desired. The average home loses a quarter of its heat energy through the roof in the winter, and suffers considerable solar heat gain through radiation and convection during the summer. To combat attic overheating and a multitude of other roofing concerns, a variety of tactics from spray foam insulation to more durable and reflective roofing materials such as standing seam metal roofs can be employed.

Together, all these systems, and many more, create a protective layer that meets both the requirements of a good building envelope and the demands of a finite planet. This is why a high performance envelope is so important. Just like the human skin, the building envelope is more than just a barrier – it is a complex and incredibly critical system of performance parts and assemblies. It regulates the interior spaces where we spend 90 percent of our time. And like the clothing we wear, it must be adaptable to all manner of weather and well-suited to its particular climate niche. It is our third skin – and something well worth investing in.

Want to build that dream home? We would love to help you.