Since readers seem to have liked my last post on preservation issues, here is another pet peeve of mine. I have worked for years with historic masonry and, like many architects who appreciate the best craftsmanship, have been consistently frustrated by the poor quality of re-pointing in many restorations. Even when the mortar used is a so-called “soft” or “historic” mix of Portland Cement, sand, and lime, the resulting mortar never looks as beautiful as the historic example that is being “replicated.” My colleagues in the field explained years ago that it was impossible to duplicate these natural lime and sand recipes because they were weak and would never stand up to modern codes. Besides, where was one going to get old fashioned slaked lime?

Well, after years of wandering in the wilderness, preservationists have a saviour. Virginia Limeworks is a company that believes in old fashioned construction techniques and has backed up their preference with products that perform beautifully and have been tested to modern standards. I have used their products and swear by them. Mix’n’Go is a premixed mortar containing only sand and natural lime. It is a mason’s dream, according to tradespeople I’ve talked to. The advantage to lime mortar is twofold: 1) the resulting mortar is completely breathable, just like the stone and brick it complements; and 2) the natural color of the sand stands out as in no other mortar mix. One never has to use a colorant or admixture. Simply get the local sand that the original masons used and combine it with lime for a beautiful wall.

Check out Virginia Limeworks when you do your next repointing project, or insist that your mason call them up. And if you are a purist, simply buy their natural lime and mix everything yourself. No need to slake the lime or grind the mortar with a pestle. Unless of course you want to risk burning your eyeballs out.

As one who has spent his career trying to convince others of the value of historic buildings, I am amused by the new alliance between the green energy folks and the National Trust for Historic Preservation. The Trust has its purpose in this democracy–mainly to remind civic minded people that “heritage” matters–but it often sounds as if it is preaching to the choir rather than leading a new movement. The Trust is always behind the curve, proclaiming yesterday’s news to people who love the past enough to tolerate a little deja vu.

The most recent issue of Historic Preservation magazine, the Trust’s main mouthpiece, featured another “green” issue, close on the heals of the first one issued last year. Not much has changed in a year as far as preservation technology is concerned, but one or two things emerged that caught my attention.  Articles on the adaptive re-use of historic buildings started to make sense as models of energy efficiency, not because the buildings were better insulated or more advanced than new structures, but because they maintained their “old” materials and technologies. It turns out that when considered holistically, older structures often make sense as examples of environmental conservation even if they haven’t been modernized.

To an architect who lived through the first energy crisis in the 1970s, and saw the preservation movement through its highs and lows, this revelation was not news. Many traditional buildings use passive heating and cooling, clever means of ventilation, and inherently sustainable materials. One bugaboo, however, has existed since I began restoring houses 30 years ago–the question of what to do about “leaky” single glazed windows. Conventional wisdom was to throw them away in favor of double glazed sashes that would seal the house and keep heat and cold inside in hostile climates.

Finally the tide has changed and preservationists have started to look at windows as pieces of the treasured fabric of older buildings that don’t need to be sacrificed to the altar of sustainability. It turns out, according to recent research, that a well-made wooden double-hung or casement, equipped with tight-fitting wood storm sash, can perform almost as well as a double-glazed unit in terms of thermal resistance and infiltration. Moreover, the cost of replacing beautifully-crafted wooden sash continues to rise, increasing their potential “embodied energy.” There is really no compelling reason to remove character-defining wood windows from any historic structure, if storm/screen units can be installed outside.

Though this may not sound revolutionary, it frees preservationists from one of the most vexing problems in building conservation. If one wants to be green, don’t install windows made of green wood. Why? The seasoned, old-growth wood in most historic windows will continue to perform better than either new wood units or comparable synthetic or metal sashes (metal conducts heat faster than wood). It turns out that when it comes to windows, they really don’t and can’t make ’em like the used to.

From now on my answer to clients who tell me their energy bills will be intolerable if they don’t replace their “leaky” windows will be: it’s not easy being green; add some foam to the roof deck.

A Twist of Fate

March 6, 2009

Previous posts concerning the folly of the New York Public Library’s $250 million dollar expansion plans have proved prophetic. Yesterday’s New York Times front page featured a report on the library’s failed attempt to sell its popular Donnell Library on 53rd Street to a developer who planned to demolish the building for yet another luxury retail, restaurant and hotel tower. Without the inflow of cash from the sale the library may not be able to follow through on its foolish scheme to have Norman Foster gut and redesign the center of Carrere & Hastings’ masterpiece on 42nd Street. Foster’s office announced a layoff of 350 staff, or 1/3 of its employees, as reported in the latest issue of Architectural Record.

Fate plays tricks on both the common folk and the high and mighty. The 10-year boom in expensive, high-rise construction throughout the globe is coming to an end, and architects like Foster, who benefited from the hubris of bigwigs throughout the world, have felt the pinch. It’s hard to feel sorry for him, or for his Arab, Chinese, Turkish, American, German and English clients. Thomas Hastings, the architect of the old library, may be chuckling from beyond the grave. He warned New Yorkers of the disastrous loss of community and urban coherence that would come from constructing tall buildings, and little good to say about modernism. Once again an economic downturn is proving good for preservation. A great building may escape unscathed.