A recent opinion piece in the New York Times targeted historic preservation as an out-of-touch field that negatively impacts communities, as well as a movement that does not support building a more sustainable, environmentally-friendly planet. Alongside the responses of my historic preservation colleagues, I’d like to respectfully disagree with the Times piece, too.
Of the dozens of ways that historic preservation makes communities more vibrant, humane, and sustainable, I’d like to highlight a little understood and little appreciated virtue and value of existing buildings – their embodied energy.
At Adirondack Architectural Heritage we’ve invented a word for this value – Embedawatt.
Let’s Start with the Watt
We’ve all heard of Watts, usually in the form of selecting a light bulb for its wattage. We understand that the higher the wattage, the brighter the light, and the more energy is used in producing that light.
The watt (W) is the International System of Units’ standard unit of power (energy per unit time), the equivalent of one joule per second. The watt specifies the rate at which electrical energy is dissipated, or the rate at which electromagnetic energy is radiated, absorbed, or dissipated.
We measure energy usage in a variety of ways. It’s the gallons of gasoline or diesel fuel we use in our cars and trucks. It’s the fuel oil or natural gas we use to heat our homes. And it’s the electricity we use for almost everything else, from appliances, to lighting, to home heating. While electricity is measured in watts and kilowatts, other fuel consumption is measured in BTUs (British Thermal Units) which can be converted into watts for comparison purposes.
Then There’s the Negawatt
In 1985, energy efficiency guru Amory Lovins coined the term Negawatt as a way of describing and measuring the energy NOT used as a result of energy conservation. This was a way of encouraging consumers to conserve energy based on a “Do Less to Use Less” attitude and to make the point that every watt/BTU not used has value too. In this case, the more Negawatts in your energy bank, the better.
If you think about meeting our energy conservation, renewal energy, and carbon reduction goals, it comes down to a couple of things:
Make personal choices to use less energy altogether. This can be done in a variety of ways we all know about: drive less, use a more fuel efficient car, take public transportation; insulate and weatherize your house, upgrade to more efficient and/or non-fossil fuel heating and cooling systems, turn the heat and air conditioning systems down; consume less; eat less meat – all of these savings go in your personal negawatt bank. Hurray, you are an energy saver!
Use more renewable energy and much less carbon-based energy (coal, gas, and oil). We also need to make huge shifts in how we produce energy in the first place and we can’t reach a truly carbon-free energy system fast enough. Besides encouraging governments and energy producers to escalate the pace of this change more quickly, we can also make individual choices to purchase our energy from renewable sources in a variety of ways, including the choice to participate in a Community Shared Solar farm. All this matters.
Introducing the Embedawatt
But there’s something else we should consider when we make choices around energy, from the kind of house we buy or build to a variety of other consumer choices we make every day, and that is to consider the value of embedded or embodied energy. Embodied energy is the energy stored in any existing material – the materials used to make an existing house, car, cans of beer – absolutely everything.
Valuing embodied energy is at the heart of why we recycle. Tossing something away is inherently wasteful, but recycling something is a smart energy choice because, for instance, making an aluminum can from recycled materials takes 95% less energy than to make a can out of raw materials or, even better, avoid cans as much as possible by using a refillable container. In the same way, reusing and rehabilitating an existing building uses less energy than to create a new building because so much of the energy to make the existing building has already been expended.
An Embedawatt represents the value of this embodied energy and this, too, can be calculated for absolutely anything. In the historic preservation field, we make the point that a building is the largest thing you’ll ever get to recycle, and that by reusing or continuing to use an existing building, you are valuing and taking advantage of its embodied energy. If Negawatts represent the value of energy not consumed, then Embedawatts represent the value of energy already spent in materials, which still often have a long and useful life.
In contrast, new buildings require a great deal of new energy, including the energy to:
- Get the raw materials out of the ground or off the land
- Transport the raw materials to the place of processing
- Process raw materials into manufactured products
- Transport the finished product to the retailer and then to the consumer
- Install the finished components into the building
Plus, when demolition of an existing structure is involved, add to the above the energy costs for the demolition work, including transportation to a landfill, and other disposal costs.
Here are the average energy costs for several common new building materials (from the Illinois Historic Preservation Agency, 1976):
- For every board foot of lumber: 1,533 watt hours (5,228 BTUs)
- For each brick: 3,980 watt hours (13,570 BTUs)
- For each cubic foot of concrete: 28,075 watt hours (95,738 BTUs)
- For each square foot of glass: 12,266 watt hours (41,828 BTUs)
- For a pound of steel: 6367 watt hours (21,711 BTUs)
- For every pound of aluminum: 26,643 watt hours (90,852 BTUs)
Put this into an average-sized new house and you get about 181,000 kilowatts in energy expenditure just to build the house.
Assuming the new house is more energy efficient than an existing house, it still takes an average of 40 years for an energy efficient new house to recover the energy and carbon expended in the construction of the house (Empty Homes Agency, 2008).
We all want to live in more energy efficient buildings but, in making good decisions, it helps to understand both the energy consumed in operating a building and the energy consumed in making a building.
Add to this the fact that existing buildings can be rehabilitated and improved to be as energy efficient as new construction, and this puts the reuse of existing buildings in a new, much more favorable light.
The greenest building just may be the one that already exists.
Read more about historic preservation at Adirondack Architectural Heritage’s webpage.
Illustrations: Above, the symbol for the Embedawatt, as envisioned by AARCH staff; and below a Medium Sized House Energy Chart courtesy of Jerry Jenkins (from Climate Change in the Adirondacks).
This is a fascinating article that I have yet to wrap my head around in it’s entirety. Thank you for making it available!
I agree. The article illuminates the many decisions we make every day that have cumulative effects on the environment. One example is American gasoline usage drops during prolonged spikes in gasoline prices. People drive less and purchase more efficient vehicles. Then that progress all goes out the window when prices drop back down and corporations regain control producing even more monstrous vehicles. Another is our ongoing switch to LED lighting – certainly lowered my electric bill. But probably the longest-reaching choices we make are at the polls.
A whole lot of common sense in this article. Thank you Mr. Englehart.
I’ve lived in both very old homes and more contemporary homes, and as a result I’ve been able to compare energy bills. Much of the energy efficiency of modern construction is thrown away due to incorporation of elaborate systems that burn power: central A/C, trash compactors, numerous bathrooms with all sorts of energy burning features, heated garages, etc. Also, the vast size of many new homes take inherently more energy to heat and cool. My small apartment in an 1860s house uses much less energy than most homes my friends live in, no matter what the age. We use A/C sparingly, because the deep basement keeps things cooler in the summer, and it also helps preserve heat in the winter. It was designed when there was no A/C so windows open wide to let in summer breezes. Large trees shade the yard. Shorter me, age of a structure does not directly correlate with energy consumption.
I agree. I live in a Sears or Monkey Wards “kit” bungalow built around the start of the depression. It is much more solidly built than an average modern home, and even many of the stick-built homes of the era. The 2x4s are actually 2″x4″! Old-growth lumber was used extensively. No plywood. My wish is that one of the previous owners hadn’t replaced the original wood sash windows with cheap, modern junk that didn’t last 20 years before failing. Properly maintained single-pane sash windows coupled with tight storm windows are very effective and have an almost unlimited lifespan. My 90 year-old attic windows are original and in great shape! Modern windows are designed to last about 15-20 years, and that is about what you get before the double-pane seals give out and need to be replaced and the weatherstripping fails. Buildings designed and constructed with disposabilty and 20-year component lifespans in mind are not always the wisest choice. Probably one of the biggest offenses to our urban landscapes was the “modernization” movement in the 60s where beautiful, 100 year old brick or wood structures were refaced with slick, texture-less, concrete facades. Luckily, many are now being uncovered and preserved.
Just a quick drive around a village or township can reveal dozens of solid, old buildings in need of stabilization and care, not demolition. Re-using and updating (only where necessary) old structures can be expensive, but ultimately may save energy, resources, and landfill space. It can also create jobs for craftsman specializing in restoring and maintaining older homes. I strongly recommend people looking for a home or business to seriously consider reusing an old structure whenever possible before building a new one. Another bonus is that it helps maintain the character of a locality as well.
It’s really quite sad to see so many nice older homes purchased and then demolished so they can be replaced by some enormous ugly contemporary home that towers over the rest of the neighborhood, and probably doubles the square footage while using more energy due to the modern systems and size.
Excellent, Mr. Engelhart. Thank you for this.
Just one thing to add. The Times article complained about historic houses in Washington being unable to put solar panels on their roofs. Haven’t they heard of solar farms? The panels are located out in the countryside and put their power on the grid. Then you buy power from the grid for your house, minus your credits for the power from your solar panels. Works great. The power you sell to the grid is renewable and you can also sign up with a renewable supplier for the power you buy, so you go green twice!
Over the past 15 years, I’ve been restoring a 19th century vernacular house in the Champlain Valley. In the process, simply by going slowly (cause I scarcely know what I’m doing) and being naturally curious, I’ve been bombarded by the lessons Steve describes over and over, but what I think most about is an energy source he doesn’t record: human life. I marvel every day at not only the LOCAL raw materials embedded in my old house, but at the human energy it took to fashion the iron ore into the square nails, the hours of sweat to produce each hand sawn and planed board, the labor required to slake lime and gather sand to plaster the walls. People think NOTHING about gutting a period Adirondack house, dishonoring that human time and energy, to say nothing of the lost record of craftsmanship and ingenuity, as well as the local raw materials, many of which can no longer be replaced.
Though I understand and love the idea that the future will be powered by renewable energy, meaning we must have all-electric homes, I am frequently reminded of the great value of having an alternate means of heating here in the north country. Several times this winter things would have been pretty bleak without the gas mains supplying abundant and cheap energy to keep our home habitable when the power went out for many hours. In our old home I can actually run the furnace manually if I need to, and my wife can turn on the oven in the kitchen to survive. It is not unheard of to have the electric down for days or even weeks at a time during the winter. We will need to have a much more robust electric infrastructure to make electric totally viable in the north country, and all of us will have to have portable generators which will depend on fossil fuels.
Another often overlooked (because it is expensive to install) means of short-term power generation is a battery system. With battery storage becoming smaller and more efficient, this is also becoming a reasonable option for some.
Sure a battery system would be great for short-term backup, but not for heating a house in below zero weather for hours or days. The reality in the north is that people will need backups to electric, which might include a wood stove, propane, or gas or some combination of them. I am reminded of several ice storms where the electric grid power was out for many days. Just a few weeks ago it was out for more than 8 hours on a bitter cold day. We were making plans to keep the pipes from freezing when it finally came back on.
I agree. With an aging and technologically vulnerable electric grid, It doesn’t make much sense to rely on electricity as a sole source of heat in a cold environment.