By Rachel David, LEED AP BD+C | Rachel is CRSA’s Sustainability Director and the coordinator for all the firm’s LEED Certified projects.
Can my historic building be green?
It’s a common question tied to the assumption that modern technologies and materials are automatically more sustainable. It can be surprising that often the greenest building is the one that is already standing.
The green is built in:
Current focus on maximizing daylight (thereby minimizing artificial daytime lighting), appropriate building orientation, using local or regional building materials, natural ventilation, building mass and native plantings are often treated like new sustainable concepts. However, these strategies are essentially a return to traditional building techniques that were enlisted out of necessity. Historically, for instance, it was cost prohibitive to import building materials from long distances and methods of heating and cooling were simplistic such that it was necessary to have natural ventilation in the summers, control heat gain and maximize daylight. Modern building technologies and cooling and heating systems have allowed us to get away from these basic and effective strategies. However, these same modern technologies can allow for innovative ways to introduce new mechanical systems into existing structures, increase insulation, and rebuild windows with insulated glass while maximizing inherent sustainable qualities.
Reuse, reuse, reuse:
Just yesterday, I witnessed a nearby historic home being demolished. While this home was admittedly in disrepair, it’s grim to watch the volume of waste that was being loaded in dumpsters to be sent to the landfill. Building reuse will not only reduce the amount of newly harvested virgin material needed for a building but will also avoid generating waste sent to the landfill when a building is demolished. The EPA estimates that construction and demolition waste accounts for 40% of the total solid waste stream in the US. While much of this waste can be recycled, it often isn’t since construction waste recycling isn’t always available, can be cost prohibitive on small projects or is seen as a hassle. Even when materials are recycled, vast amounts of energy go into remanufacturing them into a new product. Not to mention historic buildings often contain materials no longer readily available now including old-growth trees or artisan handcrafted details.
Reusing an existing building allows you to utilize the embodied energy in that structure. Embodied energy is the total energy needed to produce any material. It includes acquiring, processing, manufacturing, transporting and constructing those materials into the final building. Consider the energy necessary to manufacture just one brick that is lost when that brick is sent to the landfill, then multiply that by the thousands of bricks required to manufacture an office building or school. Then imagine the overwhelming amount of energy lost in the 1 billion square feet of buildings that are demolished and replaced with new construction in the US each year.
Think of the carbon!
A report produced by the Preservation Green Lab of the National Trust for Historic Preservation studied the potential environmental benefits of building reuse. While it’s often assumed that the energy efficiency alone that can be attained by a new building will automatically make it more environmentally sound rather than reusing an older building, the report found that it takes 10-80 years for this new efficiency to overcome the negative climate change impacts created by its construction. The majority of building types take between 20-30 years of efficient operation to compensate for the initial carbon impact of the building being built. Additionally, the study calculated that retrofitting, rather than demolishing and replacing, just 1% of the city of Portland’s office buildings and single family homes over the next ten years would help to meet 15% of their county’s total CO2 reduction targets over the next decade.
Historic buildings have a tale to tell—who lived there, who built it, what has happened there. These attributes, while not mathematically calculable, add emotional if not historic significance to a building. This connection is one of the reasons building are placed on historic registries and historic districts are made. The added significance to these buildings extends their likely survival into the future. A building with meaning and connection will be fought for and in some cases be better tended to, making it last longer, avoiding demolition and embracing the embodied energy therein. A historic building often spans the spectrum– built with the climate, environment and region in mind, it can be retained and reused to maximize its sustainable qualities and partnered with new technologies giving it lasting power and emotion to stand for generations to come.