Six Sorts of Sustainable

What is Sustainability?

“Sustainability”, at its core, simply means doing things in a way that can continue over time: cleaning up our messes as we make them instead of leaving them until they overwhelm or impoverish our grandchildren. Essentially, being sustainable is paying it forward for ourselves and our descendants.

Being “Green” in residential construction is a widely used description that generally means something sustainable, but it has also become a catch-all for several different concepts and goals. This quick overview tries to differentiate between the primary categories of recent Green building initiatives in residential architecture.

Owners in the design process for a new house or large renovation are forced to make decisions about allocating their resources. Depending on their interest in sustainable design, some or all of the six categories below can affect parameters of the project design and create choices for material selections as the project progresses. Green goals largely work in concert with each other, but a few may be in conflict with each other on a given project (especially where high-tech energy solutions meet a call for natural materials). It is valuable to rank the relative importance of the following categories, in order to provide a basis for decisions and trade-offs later on.

1. Minimize Site Impact

Single family houses are inherently worse than higher-density, multi-family approaches because they affect so much more land and change much more habitat. But for houses, focus would be on:

1. 1. Re-using previously developed lots or infill lots versus new developments.
   2. Leaving site (trees and wetlands) as undisturbed as possible, partly by minimizing the size of the house/garage footprint. Minimize grading and loss of topsoil.
   3. Eliminate the Mowed Lawn, retain native species on site
   4. Minimizing impact on water/drainage patterns by retaining rain from roof and using permeable site materials. Dark asphalt roofs and drives are particularly bad for heat gain, but all hard surfaces create rain runoff issues.
      
      STANDARDS/RESOURCES: LEED V4 for Homes/Sustainable Sites, Water Efficiency

2. Save Energy

Since electricity, gas, and oil production have negative ecological impact including Global Warming, a major Green goal is to minimize the amount of off-site energy used in daily living. Building a Passive House with net-zero energy use is the ultimate challenge here, but any and everything that makes a house more efficient is a step in the right direction. Methods include:

1. 1. Employing super-insulation and air-sealing to bring energy loss close to nothing. Closed-cell foam, ultra-thick insulated walls without thermal bridging, and extreme performance windows are typically employed.
   2. Sealing off potential leaks using newer air-sealing methods avoids energy loss, but also makes mechanical ventilation very important. Energy-Recovery Ventilators avoid exhausting conditioned air.
   3. Engineering high-efficiency mechanical systems is a must. They can be high-tech HVAC systems, maybe using geo-thermal energy – but much smaller to reflect a super-insulating envelope. To actually achieve Net-Zero standards, some renewable energy generation such as solar or wind-powered would be required.
   4. Passive heat-gain or storage includes using heat-sinks such as masonry walls to soak up and retain the sun’s warmth overnight; passive cooling includes using the chimney effect and natural ventilation to exhaust hot air.
   5. LED lighting is a must to reduce energy used on lighting by almost eighty percent while producing huge life-cycle cost savings. Fans can move air to increase comfort instead of using air-conditioning in warm months.
      
      STANDARDS/RESOURCES: PHIUS (Passive House); LEED Zero; Zero Energy - International Living Future Institute

3. Shrink Carbon Footprint

A measure of how much energy is embodied within a given material after transport to the site to be used in a structure. Bricks are kiln-fired at high temperatures, while local river rock has no carbon footprint except the mortar. But Carrera marble from Italy is cut and transported, which all takes energy. Aluminum takes high temperature to smelt and has a big carbon footprint, but it is easily recycled so has little impact in its second use; steel is also energy-intensive. Every material has different considerations, but notable ‘good’ or small carbon footprints include bamboo, other fast-growing renewable woods. Use of recycled materials would also enter into this discussion.

STANDARDS/RESOURCES: LEED V4 for Homes/ Materials and Resources; EPDs [environmental product declarations]; BuildingGreen.com

4. Build Material Life-Cycle and Waste

Will a material last forever or will it wear out? How will it be discarded? Throwing away wood is different from throwing away PVC in vinyl siding or Azek: bio-degradable materials are a focus. Recyclable materials are good, but only if the second use has value and if the energy of conversion is not too high. Also, even if materials are durable, they would be discarded when structure is altered or replaced. RE-USABLE materials would be the highest goal since needs and houses inevitably change.

This aspect of Sustainability has not been emphasized enough and is the focus of the Elements of Living Construction System, which finally envisions Re-Use of ALL BUILDING COMPONENTS

STANDARDS/RESOURCES: LEED V4 for Homes/ Materials and Resources; EPDs [environmental product declarations]; BuildingGreen.com

5. Use Healthy/Natural Materials: 

No off-gassing. Eliminate toxic chemicals. Focus: finishes. Paint and stain, furniture, carpet. Some materials that may be great insulators, such as spray foam, may also have off-gassing or chemical makeups that pose a problem here. Advanced air-filtration technologies can be a focus.

Outside your home, eliminate fertilizer, pesticides/herbicides, and the mowed lawn. Prevent air in the garage from contaminating air in the house.

STANDARDS/RESOURCES: WELL V2 – International Well Building Institute; Healthy Building Network; National Green Building Standard® -NGBS Green Certified materials

6. Green DESIGN relates to both process and form:

1. The LEED process for homes as defined by the US Green Building Council (or the National Green Building Standard defined by the National Home Builder’s Association) provides a design process standard that can result in Green Certification of the house upon completion of the project. See LEED V4 for Homes/ Innovation in Design Process
2. What makes a building more intimately related to its environment? How does the form reflect the vision? Green product specification alone does not necessarily create an architectural structure that reflects the values of sustainable living and harmony with our environment.

Sustainable design has not yet developed a coherent visual language, nor is there a single style of Green. The EoL Homes design series is my interpretation of what a truly Sustainable house could become -- George Clemens, A.I.A.