How Long Is This Gonna Last?

When I was in architecture school, people often talked about “building for 500 years.” The architecture program at my alma mater, the University of Notre Dame, is a classical program, steeped in the traditions of ancient Greece and Rome, so this timeframe is not a surprise. For the past 5 decades, all architecture students at Notre Dame have spent an entire school year in Rome, in the middle of their degree program, studying the city and its buildings. Rome is a fascinating city, with many ancient buildings, or at least parts of many ancient buildings, still intact, and in most cases still in use. Usually the buildings being reused have been adapted to be something other than what they were originally built for. A great example of this is the Theatre of Marcellus, built as an open air theatre similar to the Colosseum in ancient times, but then partly used for parts (stone) for other structures, then turned into a fort, then turned into a palazzo (a private palace), and then later turned into apartments. It continues to be used as apartments, and still includes parts of the ancient building. You can see parts of the building from different eras in the photo below (some ancient, some restoration of the ancient, and some of the newer apartments at the top).

Theatre of Marcellus, Rome, photo by Liz O’Sullivan

It’s mostly just an accident that buildings like this have lasted this long. I’m sure the builders of the original theatre didn’t envision it lasting over two millennia. But they used the construction materials, building methods, and knowledge they had – they didn’t have many choices. If they wanted something to last for more than a year, they pretty much had to build it in such a way that it might last thousands of years.


Here in the New World, up in the mountains in Colorado, we often see old miners’ cabins in various stages of deconstruction, decay, stabilization, or restoration.

Miner’s Cabin, Colorado, photo by Liz O’Sullivan

A silver miner probably built the cabin in the photo above – silver mines operated near this cabin starting in the 1870’s – but the actual age of the cabin is unclear. It’s obviously no longer in use. It long ago outlived its usefulness in this terribly harsh spot over 12,000 feet above sea level, above treeline, directly below several 14,000 foot high mountain peaks, whose flanks still have old abandoned mines all over the place – yet the cabin remains. How long was this cabin supposed to last? We don’t know, but in order to build a habitable shelter that would withstand the fierce winds coming down from the mountain peaks, and the tremendous wintertime snow loads, for as long as the miner’s luck or determination held, the builder had to use materials accessible in this remote area (primarily evergreen trees cut from the forest nearby), and the available knowledge at the time. So it stands today, probably accidentally.


Today in most of the U.S. we have many choices of building materials and methods. Usually, the more durable and resilient materials are more expensive, so building owners who are building to hold for less than a decade are going to choose less-expensive materials so that they end up with buildings that serve them well, with little repair or expensive maintenance, for only as long as they intend to hold them. What happens next to the buildings doesn’t matter much to the first short-term owners. But owners who intend to hold buildings for the foreseeable future (maybe a university, a hospital, a public school, or a government) usually carefully consider and weigh the desired lifespan of the building, desired or budgeted maintenance and repair costs, and construction costs. Almost no one has an unlimited budget for construction costs, but some owners do have enough so that they can build in ways that most owners no longer build. Most people don’t pay for double-wythe clay masonry exterior walls as a general rule for institutional buildings, but at least one university that I know of has made this a standard for their campus in recent decades. Some owners only have enough construction budget to build their exterior walls with studs and OSB sheathing, even if their plan counts on the building’s lasting for more than 25 years. They just have to hope that no catastrophic water damage event occurs. In rising floodwaters, a building with an exterior wall assembly with less-durable or less-resilient materials that get soaked will fare much worse than a building with double-wythe clay masonry exterior walls, and may even have to be demolished well before the end of its originally-planned life.


Some old buildings accidentally ended up being long-lasting; some new buildings accidentally end up being temporary. Older methods of construction are more durable and resilient by default, and are more expensive. Some of our newer methods, which can pencil out to make more financial sense for an owner’s intentions for the building, cannot withstand some disasters, or even minor water damage over a long term, and buildings can end up being a total loss before their planned ends. What a waste, in the big picture.

But some buildings are actually meant to be truly temporary.


When Denver restaurants reopened after closing in the early days of Covid, they were allowed to apply for permits to expand seating into the right-of-way and parking lots. Denver has a sunny, dry climate, and if they can get it, restaurants have outdoor patio or sidewalk tables for diners – used almost all year round, even in winter, even when there is no pandemic, at sunny noontimes. We love to be outdoors. But it can get very, very cold in Denver in the fall, winter and spring. When Covid-19 combined with chilly weather, Denver saw a proliferation of small temporary buildings, set up on sidewalks, parking lots, and even streets near restaurants.


None of these temporary buildings is great. Many are small greenhouses with doors, repurposed to be tiny dining rooms with one table inside, scattered around parking lots or restaurant patios. Some are large event tents, set up on sidewalks or streets, with two ends open, and a mess of hoses, cables, and propane tanks to bring electricity and heat for a dozen tables of mostly-outdoor diners. Some are wood shed-type structures, with individual booths in partitioned areas under the roof, and curtains making up one wall. Denverites have been stepping over power cords on sidewalks and avoiding flapping plastic “walls” for months. The restauranteurs were lucky to get these structures – they quickly became hard to procure.


Last month, I ate inside at a restaurant for the first time in over 13 months, to celebrate my husband’s birthday. Well, we were inside, but technically we weren’t in the restaurant. We were in a very thoughtfully designed and constructed temporary “outdoor private bungalow” located on a before-times parking lot, 2 doors down from the restaurant. Instead of the quick-we-need-something-that-we-can-make-do-with approach that most restaurants seemed to take, this restaurant actually had their outdoor bungalows designed and constructed to fit their specific needs. The structures have no floors, but they have rugs. Ours was big enough for a table for 4, but didn’t feel too big for the 2 of us. Each structure has electric heating, nice lighting, a glass door on a closer, and a slider window next to the door. Interior wiring is concealed and thoughtfully routed, outdoor wiring and lighting were carefully installed. The bottoms of the walls are opaque, possibly fiber cement panels, the top parts of the walls are translucent polycarbonate. The roof, a white corrugated shed roof, drains thoughtfully. There are about 18 of these, most in rows of up to 6, with shared walls, in this parking lot.

Covid-Era Outdoor Dining Bungalows, Denver, photo by Liz O’Sullivan


How did one restaurant have such an ideal designed-to-order solution while others scrambled to make do with flimsy greenhouses or tents? Planning. If I recall correctly, this restaurant appeared to me to be late to the game of outdoor dining shelters – but now I know that was probably because they were planning and constructing, while others were popping ready-made things into place. In late September of 2020, the City of Denver announced that restaurants could apply to continue to operate in the public right-of-way or in parking lots through October 2021. So, that announcement set a lifespan of about a year for a temporary outdoor dining structure, one important known thing in a sea of unknowns. This restaurant has had a large following of loyal patrons for almost 3 decades. They kept up a curbside pickup program during the Covid-shutdown days. It’s located in a neighborhood where many people eat out many nights of the week and walk to their favorite restaurants. Employee turnover is low – servers work at the restaurant for years. So although no one could guarantee anything at any time during the early days of Covid, this restaurant is more stable than many, and was sure to have continued patronage at some minimum level.


The restaurant set some requirements for use of the “private bungalows” – reservations in advance, reservation deposits, fixed price 4-course menu only, and a strict 2-hour maximum use time limit, due to a neighborhood requirement that they close the outdoor dining at 10 pm on weekdays and 11 pm on weekends. This restaurant was able to determine some knowns on their own. But my guess is that the biggest piece of this puzzle had to be the permission to keep the outdoor dining bungalows erected through October 2021 – setting a lifespan. Presumably the restaurant could budget based on these things. (Knowing how much diners would spend, knowing the maximum amount of time they’d stay, knowing how long the private dining bungalows could stay in place.) The structures only have to be weathertight for a year. The windows and doors only have to operate smoothly and look good for a year. The thin solid walls only have to resist weathering and look okay for a year. In these very uncertain times, this restaurant was able to take the knowns set by the City, create some of their own knowns, and work with those to come up with a budget for their temporary structures.


Denver became full of temporary structures due to Covid. We have drive through tents and sheds for Covid testing set up in parking lots. There are hundreds of camping tents and tarps set up on unoccupied properties and the strip between sidewalk and street where increased numbers of people experiencing homelessness are living all over the city. Restaurants have the aforementioned strange little greenhouses for private outdoor dining. Our friends’ backyards began to include makeshift roofless enclosures around firepits for socially-distanced dead-of-winter small gatherings. As these things cropped up, I became interested in temporary structures in a way I never imagined I would. Mostly, I have wondered what will happen to the temporary structures when they are no longer needed, or when they start to fall apart. I’m always going to prefer that cities be filled with resilient long-lasting structures, but temporary buildings might continue to have their places in cities too – and these are better when they’re thoughtfully conceived and executed.

Water lapping at the first step of an entry, Doge’s Palace, Venice. This happens all the time, yet the centuries-old building, made of solid stone masonry, is still standing.
Photo by Liz O’Sullivan

Old Mansion, New Office

I’ve settled in to my new office.

At the beginning of January, I moved my office from a 1972 building in Cherry Creek to a 1920 building in Capitol Hill.  Although there’s so much to love about my new office, the gentle hot-water heating and the natural light are at the top of my list.  The loud 1970’s HVAC and fluorescent lights in the old office were wearing on me.

I’m now in the Historic Kistler-Rodriguez House.  Here’s an old photo, which I copied from the nomination form for the building’s historic designation.

Kistler-Rodriguez House old photo

 

Denver’s Capitol Hill has a number of large old mansions that are currently used as office buildings.  There’s an interesting reason for this.  Denver’s 1957 zoning code drastically “up-zoned” Capitol Hill, which at that time was covered with single-family houses, to residential high-rise zoning.

Capitol Hill’s proximity to downtown Denver makes its land valuable, so demolishing houses to make way for high-rises started to make a lot of economic sense.  But Denver’s citizens didn’t want all of its historic mansions destroyed, so an interesting exception was carved out in the zoning code to allow for designated Historic buildings in residential-zoned districts to be used for office use.

The highest and best use for these properties was suddenly less clear. Demolition to make way for more dense income-producing residential buildings was no longer necessary; with a few alterations, these buildings could generate more income per-square-foot as office buildings than they could as residential buildings.  This exception saved many historic buildings from destruction by allowing them to produce more income for their owners than residential use could, which de-incentivized their demolition.

Shortly after the photo above was taken in 1982, a “glass box” addition was added to the south side of the building.  It’s a pretty cool addition, and, to use a word favored among architects, a nice juxtaposition of 1920’s and 1980’s.

The Kistler-Rodriguez House, also known as the Dominican Republic Consulate, was designed by Jules J.B. Benedict, and was built in 1920. It was designated (entered into the National Register of Historic Places) in 1983.

I’ve often called the building the “Governor’s Park Dental” building, because my dentist has been the main tenant of the building for the last 30 years.

The Denver Public Library has more information on the building here, and here’s a link to the National Register Nomination Form that was submitted to the Department of the Interior.

Working on historic preservation in Denver is still important today. Among other things, Capitol Hill United Neighborhoods (CHUN) Historic Preservation Committee works on getting historic buildings designated as Historic.  To get involved, start by learning more, here.

Cool Pictures of Old Buildings

There’s a Frank Lloyd Wright-designed house in Phoenix that’s at risk of being demolished in a couple of months.  Here’s the New York Times article about it.  After Mike Brady, Frank Lloyd Wright is the most famous American architect ever,1 so how is this happening?  How is it possible that cool buildings designed by famous architects can get knocked down?  The answer is that sometimes the people who want to save them just get there too late.

But this post isn’t about “The Brady Bunch,” Frank Lloyd Wright, or mid-century modern homes.  It’s about Denver and its heritage.  Right here in Denver, buildings by less famous architects, buildings that are integral parts of their neighborhoods, buildings that are important parts of the city’s history, are at risk.

Once in a while, a century-old masonry building, that, with careful maintenance, would still be around for another 100 years, gets razed to make way for new construction.  Most of the new construction in Denver is unlikely to last as long as 50 years.  This type of replacement is not sustainable, this is not green, this is not good for Denver’s urban fabric and its urban dwellers.  People need to become aware of these buildings early, before they become at risk of destruction.  Sure, there are property rights issues that arise sometimes, but if we start talking about rights, we cannot ignore the property rights of the surrounding property owners, and the rights of the citizens to these parts of their heritage.

On to the cool pictures of the old buildings – or the links to them, anyway…

Two really special buildings that I’ve been in recently, the Croke-Patterson-Campbell Mansion and the Wilbur S. Raymond House, have been preserved and restored, and are currently the homes to a couple of bed and breakfasts.

Here’s a great old photo of Denver’s Croke-Patterson-Campbell Mansion, taken in 1892.  It looks almost too fantastic to be real.  The building has since lost some of that magnificent chimney, and many of the finials, but it’s still breathtakingly beautiful – here’s a recent photo (scroll down after the page opens).  The Croke-Patterson-Campbell Mansion has just started to operate as a bed and breakfast, the Patterson Inn.

Sadly, much of the original neighborhood fabric around the Croke-Patterson-Campbell Mansion has been lost.  But the Wilbur S. Raymond House is very much a part of a historic Denver neighborhood, the Wyman Historic District.  Here’s an old photo of the Raymond House.  It’s been the Castle Marne Bed and Breakfast since 1989.  This is my favorite image of the more recent images I’ve found online.  Here’s a good image showing its famous roses.

The neighborhood fabric and the Wilbur S. Raymond House enhance and enrich each other.  Cities aren’t made up of scattered signature buildings, and historic preservation shouldn’t be approached in that manner, either.  Cities are composed of neighborhoods, which are composed of buildings of varying significance.  We need to protect special buildings, but we need to go a step further and also protect the individual historic buildings that may not be as prominent, but without which, historic neighborhoods would not be complete.  Obviously, important buildings are at risk (such as that Frank Lloyd Wright house in Phoenix).  But neighborhood fabric buildings may be even more at risk.

Historic buildings are irreplaceable, whether they’re outstanding, or more “background” buildings.  As an architect and architectural specifications writer, and the owner of an old house, I’m intimately familiar with the differences between the construction practices of today and the construction practices of a century ago.  Buildings are not built the way they used to be.  In other words, “they don’t make ‘em like that anymore.”  (“They” could, but “they” don’t.)  Old masonry buildings are more durable, they can take much more neglect and mistreatment, than new buildings (even new buildings with brick on the outside).  It’s because of building science – a topic for another post.

Architects, engineers, and constructors cannot make up for occupant behavior in most new construction, but old buildings, with plaster finishes, hardwood floors, and multi-wythe loadbearing masonry exterior walls, can take some abuse and neglect from occupants, and will continue to be able to withstand use.  Old buildings can often be adapted to new uses, whereas buildings built in the last 50 years are usually difficult to use for purposes other than their original uses.  Multi-wythe masonry walls and plaster finishes are more forgiving of moisture intrusion than buildings built with newer methods of brick veneer on exterior framing, and gypsum board finishes.

People used to build with multi-wythe masonry and plaster because they didn’t have other good options.  Today, we have less-expensive (and less-durable) options, which have made multi-wythe masonry and plaster much more expensive options.  If you want a durable building, in the long run, it’s probably a better value to use what you already have… and preserve an old building.

I encourage people who are interested in helping to preserve our built heritage to get involved with local preservation groups.  If you live in Greater Capitol Hill in Denver, as I do, your local preservation group is the CHUN (Capitol Hill United Neighborhoods) Historic Preservation Committee.  (If you don’t know what your group is, but want to get involved, leave a comment on this post and I’ll help you find your group.)

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Notes:

  1. I have to thank Jules Dingle for the Mike Brady comment.  Sophomore year in college, Jules said that Mike Brady is the most famous American architect.  Obviously, that comment still cracks me up today.

For further reading:

  1. In 1967, the City of Denver, in the Landmark Preservation Ordinance in the Municipal Code, declared that “the protection, enhancement, perpetuation and use of structures and districts of historical, architectural or geographic significance, located within the city or its mountain parks, is a public necessity, and is required in the interest of the prosperity, civic pride and general welfare of the people.”  And that “the economic, cultural and aesthetic standing of this city cannot be maintained or enhanced by disregarding the historical, architectural and geographic heritage of the city and by ignoring the destruction or defacement of such cultural assets.”
  2. Denver’s ordinance followed the National Historic Preservation Act of 1966, in which the U.S. decided that“the preservation of this irreplaceable heritage is in the public interest so that its vital legacy of cultural, educational, aesthetic, inspirational, economic, and energy benefits will be maintained and enriched for future generations of Americans,” and that “although the major burdens of historic preservation have been borne and major efforts initiated by private agencies and individuals, and both should continue to play a vital role, it is nevertheless necessary and appropriate for the Federal Government to accelerate its historic preservation programs and activities, to give maximum encouragement to agencies and individuals undertaking preservation by private means, and to assist State and local governments and the National Trust for Historic Preservation in the United States to expand and accelerate their historic preservation programs and activities.”

While You’re the Caretaker of an Old Brick Building…

We’re doing some maintenance work on our home, a 1904 brick foursquare in Denver (a “Denver Square”).  Someone painted the brick years before we bought it, and it’s time for fresh paint.  Preparation of the brick for repainting revealed that we needed much more repointing (tuckpointing) of the mortar joints than I had anticipated.  So… what does that mean?

Old brick buildings are really interesting.  The brick is often pretty “soft,” and the mortar is even “softer.”  By soft, I mean that you can gouge it or wear it away pretty easily; it’s, well, kind of weak.  Our house has butter joints – really skinny mortar joints – with mortar color that matched the brick color.  The house must have been so beautiful before someone came up with the “genius” idea of painting the brick… but I suspect that they painted because they thought they could substitute painting for repointing those mortar joints.  Well, now we’re repainting AND repointing, so THAT didn’t work!  Whoever made that decision decades ago really wasn’t acting in the best interests of the house.  Sometimes, it’s better to do nothing at all than to do the wrong thing to a building.

Masonry walls need to be able to let water out, and need to be able to let water VAPOR out, and individual bricks in a wall need to be able to move a bit, in case they expand due to water absorption.  Yes, bricks are a bit porous, and water gets into brick walls.  You just can’t keep water out, so you always need to provide ways for it to GET out.  Unless you want damaged bricks, you need the bricks to be able to move, and you need the brick wall to be able to “breathe,” at the locations of the mortar joints, so you need the mortar to be “softer” than the brick (weaker and more porous).

When it’s time to do repairs on an old brick building, you need someone who knows how to do it right.  (Mortar-in-a-tube is not the right thing to use on an old building!  Old mortar was made with much more lime than today’s mixes have – for old masonry, you really need a specialist.)  We hired a mason who specializes in restoration of historic masonry.  No, we didn’t need some of the fancy things that masonry restorers are capable of doing, such as matching new mortar color to the existing historic mortar color.  (Ours will be painted over).  But not everything that we do for buildings is for appearances.  Much of what the caretakers (you know, the owners) of old buildings need to be doing is for the long-term FUNCTIONING and durability of the buildings.  Building elements that function well, and are durable for the long-term, contribute greatly to the beauty of buildings.

Durability should be a primary focus of the sustainable (green) building movement.  Build buildings well in the first place, maintain them properly over the years, and keep all that embodied energy in our cities instead of sending it off to landfills.  Some well-meaning people are trying to ram an ethic of sustainability into a throw-away society, and it’s just not gonna work unless we develop, train, and properly compensate, our skilled building tradespeople, and develop in homeowners a strong sense of needing to care for their buildings, instead of just selling and leaving when maintenance needs present themselves.

I got off an important tangent up there.  Back to that paint – the new paint is a necessary evil for my house, since someone already painted the brick years ago.  Paint that is firmly attached to old brick should not be removed – removing the paint almost always removes the toughest part of the brick – the part that got fired.  The inside of the brick is a bit softer than the exterior fired surface, so once a historic brick building has been painted, it should remain painted.  Removing the paint could cause the brick to slowly erode away.  However – you want paint that will not keep water in that wall.  You want paint that can “breathe.”  Flat paint typically is more vapor permeable than glossy paint, and latex paint is more vapor permeable than alkyd or oil-based paint, so if you have to paint brick, use flat latex paint.  I wanted flat paint for aesthetic reasons, so I was thrilled to find out from Diane Travis at the Rocky Mountain Masonry Institute that I was on the right track functionally with flat paint because of its higher vapor permeability.  Diane emailed me this great brochure on “Maintenance and Repair of Older Masonry Buildings” when I contacted her for masonry contractor recommendations.  The brochure is a good resource, and so is the Rocky Mountain Masonry Institute!  You can download a copy of the brochure if you click here.

Regarding those skilled tradespeople – I got two recommendations for masonry contractors who specialize in historic masonry repair and restoration.  Both contractors were highly recommended, and were recommended by more than one person.  Both do commercial and residential work.  I met with Gary Holt of Olde English Masonry  and John Voelker of Cornerstone Restoration, and we hired Cornerstone because of schedule availability.  Cornerstone did great work.  If you need a masonry specialist, either contractor would be great.  They’re both busy, so plan ahead.  Your old brick building deserves to be maintained by an expert.  While you’re the caretaker of an old brick building, do the right thing for your brick.

City’s History Should Trump Developer’s Economic Feasibility

Yesterday’s Denver Post featured an article written by Tina Griego about the old Cathedral High School buildings at 1840 Grant, in Denver. http://www.denverpost.com/search/ci_19225279 

Sagebrush Capital, a developer who is under contract with the Archdiocese of Denver to buy the property, intends to demolish all the buildings and build an apartment complex on the site.  Sagebrush’s application for a certificate of non-historic designation from the city (a precursor to an application for a demolition permit) prompted city planners to open up a time period to allow people to apply for the building to be designated as a Landmark Structure.

According to the article, city planning staff describes some of the complex as representing “an exemplary example of Spanish Renaissance Revival style by a noted architect.”

A representative of Sagebrush Capital says that “it’s not materially, structurally or economically feasible to redevelop these buildings.”  It’s often not economically feasible for for-profit companies to redevelop historic structures.  However, the question of material and structural feasibility should be answered by a different party.

In order to preserve the character of a city, the qualities that create a sense of place and set one city apart from another city, city planners need to think beyond short-term economic growth.  Retaining the features that make up the unique feel of a city has to be a priority over other things such as economic development.  (Imagine if planners all over the country were to approve every proposed demolition and development in every city.  In a matter of decades, Denver, Atlanta, Dallas and Charlotte could be virtually indistinguishable from each other.)

The law of our city actually states that the preservation of such exemplary buildings is a public necessity.  Denver’s Code of Ordinances contains a chapter on Landmark Preservation, in which it states that:

It is hereby declared as a matter of public policy that the protection, enhancement, perpetuation and use of structures and districts of historical, architectural or geographic significance, located within the city or its mountain parks, is a public necessity, and is required in the interest of the prosperity, civic pride and general welfare of the people.” – Denver, Colorado, Code of Ordinances, Title II – Revised Municipal Code, Chapter 30 – Landmark Preservation, Article I. – In General, Paragraph 1.

Some of these buildings at the Cathedral High School complex are irreplaceable.  Buildings such as these contribute to the character of our city in a way that cannot be duplicated with new construction.  Historic buildings often act as a cornerstone for neighborhoods, and are a source of local pride for good reason – they’re unique and memorable.  What makes Denver the city it is?  What happens when that historic character is “all used up”?  At that point, why would anyone want to live in (or build in) Denver, if similar nondescript opportunities for living (or building) are more economically feasible elsewhere?

I will be extremely disappointed if Landmark Preservation Commission does not recommend to City Council that the exemplary buildings be designated as Landmark Structures.  I will be extremely disappointed if City Council does not vote to designate the exemplary buildings as Landmark Structures. 

The long-term benefits of preserving the special things about Denver, including historic buildings that contribute to the character of our neighborhoods, need to be a higher priority than any short-term economic benefit.

Additions to Historic Buildings

I believe that there should be a clear separation between an original historic building and an addition to that historic building.  I happen to strongly prefer traditional additions onto historic buildings, but I consider my style preference to be personal, and not something that should be dictated by historic preservation guidelines or zoning codes. 

I want to see the historic building as its own entity expanded by what is obviously a later addition.  I do not want to see a historic building with an addition with brick toothed in and a new seamless roof over the entire building.  This misleads future observers of historic buildings into believing that the building was originally built that way.  It waters down future observers’ understanding of the integrity of historic forms and construction methods.

Old Windows, LEED®, and Historic Character

We have storm windows on the outside of the original windows on our century-old house in Denver.  From inside our home, I get to enjoy the wavy character of the old glass and the beauty of the old wood.  I try to discourage neighbors and friends from window replacement, and encourage them to get storm windows instead.  LEED® encourages window replacement, but it shouldn’t.  Here’s why, taken straight from a publication by the National Institute of Building Sciences:

“LEED® fails to acknowledge that historic windows are important features and that their energy efficiency can be upgraded.  LEED® encourages the use of highly energy efficient windows, which often requires the removal of historic windows that are potentially reusable.  Moreover, original windows are character-defining features of historic buildings and their removal can significantly alter a structure’s integrity, thus conflicting with preservation goals and the Secretary’s Standards.

“With proper maintenance, windows built from old growth wood can function indefinitely and their performance can be substantially bolstered by using storm windows, caulk, and weather-stripping.  Studies have shown that these simple improvements can result in efficiency similar to that of new insulated glass windows.  Modern windows also have a relatively short lifespan and can be difficult, if not impossible, to repair.  Once modern windows fail, there are few ways they can be recycled, and they will likely end up in landfills.  This begins an environmentally insensitive cycle of removal and replacement.

“Therefore, the most responsible approach is to retain historic windows that last and retrofit them with increased effectiveness rather than install new windows that, without exception, will fail and cannot be repaired.  Regrettably, the replacement window industry is strong, and old windows are touted as poor performers, so the common practice of replacing windows in not likely to change much in the immediate future.  To combat this, LEED® should consider awarding points for the repair and continued use of old windows where significant improvements in energy efficiency are demonstrated, as well as where significant amounts of historic fabric are being retained and reused.”  –  National Institute of Building Sciences, Whole Building Design Guide, WBDG13 “Strategies for Sustainable Historic Preservation”

The bold text above highlights the important issue.  The most sustainable thing to use is what you already have, especially when it’s as precious as a historic window.