Sustainability in Buildings: High-Tech or Low-Tech
If you have sustainability goals for your project, it may be difficult to know whether low-tech, passive strategies are the way to go, or if high-tech solutions are going to better meet your goals. Here, we’ll walk you through when to crunch numbers and when to just follow your gut.
June 9, 2022
To most of us, the techy-ness of building green can be overwhelming. If you ask an architect, mechanical engineer, or energy consultant how to limit your project’s carbon footprint, you’ll get completely different answers.
Energy modeling – the process of analyzing how a building will perform once it’s built – can be a cost-intensive and complex process. In addition, many high-tech products are touted in the building industry as the “solution” to building sustainably.
Do we actually need reversible vapor barriers, heat recovery ventilators, or any of the myriad sustainability options out there?
Use low-tech strategies as rules of (green) thumb.
The good news is that following some simple rules of thumb will get you most of the way to a low-carbon project.
Sustainability has more to do with a building’s size and shape than you might think! Smaller dwellings take less energy to heat and cool, and are, generally, inherently more sustainable than larger ones.
Remodel an Existing Building
Building new construction involves putting the most “embodied” energy — the energy involved in creating and transporting materials — into the carbon sinkhole. If it’s possible to remodel a building to meet your needs, and it can be a complete energy retrofit, that will almost always be a better choice from a carbon perspective.
Insulate to a High Level
In our hometown Seattle’s climate, this means 2x6 walls with at least two inches of continuous insulation on the outside. This will get you to a preferred R-value (how well insulation can resist heat flow) and the continuous insulation will eliminate thermal bridging (the movement of heat from less to more conductive materials) at framing.
Use Triple-Pane Windows
As the name suggests, triple-pane windows are composed of three glass panes in a single window. They’re much more efficient than their single-pane counterparts and moderately more efficient than double-pane windows. They can require more building materials to support their heavier structure, but you’ll make up those costs with lower heating and cooling bills.
Detail for Airtightness
Use a liquid-applied weather barrier rather than a sheet product, like Tyvek, to protect walls against the elements. Not only will it make walls more durable, but it will create a more airtight seal. This matters more than you think when it comes to keeping conditioned air where you want it – inside the building. A peel-and-stick product is the next best thing to liquid applied barriers.
Ensure that your project has enough windows that you won’t be tempted to turn on the lights during the day. However, limit windows size in proportion to the exterior wall, or you’ll sacrifice heat loss (or unwanted heat gain).
Find the Right Contractor
Find the right contractor who has experience with high-performance building. They will be best equipped to detail the project correctly, ensuring that your project performs the best it can.
Go the extra mile with high-tech strategies.
Once you’ve followed the basic guidelines for a sustainable project, you have the choice to go the extra mile to ensure it has the lowest possible carbon footprint. These are things that usually involve the help of a qualified professional.
Predictive, energy modeling software that takes a building's climate, orientation, shape, and construction detailing into account can tell us very accurately how much energy a building will use throughout its lifetime. At Board & Vellum, our Certified Passive House Consultants use energy modeling to help our clients understand the full scope of their home or building’s energy needs.
If you’re spending a lot on high-end mechanical equipment, it makes sense to get it fine-tuned after it's installed to make sure you’re getting both the comfort and the performance that you’re paying for. Find someone who is familiar with the equipment you’re using and understands your efficiency goals.
Experts in envelope performance can advise on the best way to detail walls, roofs, floors, and the transitions between these things. This can ensure the durability of the building by protecting it from moisture damage and help find additional ways to improve thermal performance.
Construction Phase Verifying
Passive House Verifiers make a few site visits to a project while it’s under construction to make sure it’s getting built according to plan. This ensures you get the energy performance and comfort value that you’ve paid for.
How do you decide when to follow the rules of thumb and when to go the extra mile?
It can be hard to know without a little research whether you should stick with more passive strategies or go further to get exactly what you want out of your home. We think an energy model is an important tool for all projects seeking sustainability goals.
An energy model may optimize a design to the perfect combination of efficiency and cost-effectiveness. For example, the energy model’s results may reveal that you can get the same performance overall if you add an extra inch of insulation but reduce the R-value of the windows, resulting in an overall less expensive project. A building is too complex and has too many variables to make such results intuitive, and the kinds of insights from an energy model can be valuable enough to more than pay for the time that the energy consultant spent analyzing the project.
Ultimately, it’s likely worth putting design effort into a project commensurate with the overall value of the project. If the project is going to be your home or workspace, consider the value of your comfort and your bottom line down the road — it may be well worth the effort to go the extra mile.