Putting aside the elegance, character, and craftsmanship of these buildings, the simplicity of the building systems can make it very difficult to score very many LEED credits when renovating one of these structures. Not much is designed to change when modernizing many historical buildings.
One of the essential requirements for these building programs will be preserving the existing appearance, materials, and ambience. If you were to go through the certification scorecard used to inventory LEED compliance, you would be hard pressed to reach the minimum 26 point level of certification. Preservation and innovation seem to be conflict with each other. Chances are, the building and its contents have already been preserved for a century or more, so you shouldn't mess with success.
Based on my discussions with these professionals, we came up with several interesting obstacles to scoring green design success. Here are a few of preservation-innovation hurdles to overcome:
- Many of the mechanical systems are simple, with few moving parts and low building automation complexity. Due to the volume of the space, IAQ is usually not a problem that would require large central air-handling systems or the need for carbon dioxide monitoring. Why add complexity to simplicity if it has adequately worked for the past 100 years?
- These places frequently have very few occupants at any one time to justify peak outdoor air demand control, so purging the build to improve IAQ doesn't seem to be an issue. For the most part, historic buildings such as churches, libraries, and museums will be unoccupied more often then occupied. Adequate air quality just isn't a sustainable issue. Instead, a cool damp environment may be the bigger concern, and solutions may involve increasing energy consumption, not reducing it.
- Volume of space also puts less demand on air conditioning or ventilation. These spaces challenge the design engineer in much different ways than the design criteria for a large space with 10-ft ceilings. Specially treated, isolated room(s) within a historical building may be the only area needing a controlled HVAC, environment for things like precious books or paintings. As a result, HVAC systems may be limited in size and capacity.
- With limited ventilation fan size, there usually won't be drafts in these high-volume spaces to generate comfort complaints requiring increase space temperature zoning. Instead, these systems tend to be very limited in zoning per square foot, with minimum thermostatic control. The same can be said about lighting control points, too. Not much chance for natural lighting with task- or limited spot-lighting the more obvious choices. Most modernization situations minimize or eliminate the opportunity to include many of the lighting credits to the scorecard.
- Existing materials within these structures are, for the most part, hard surfaces with little fabric to deteriorate, thus eliminating the need for introducing sustainable materials to increase the scorecard total. Chances are the existing materials will continue to be used, so credit for recycling materials doesn't make the scorecard, either.
- Increasing the building thermal efficiency (by improving exterior insulation values) doesn't lend itself to these special renovation projects because most building exterior and interior surfaces want to remain as is to preserve the historical value and character of the building. Consideration to optimize energy performance for 2, 4, 6, or 8 credits is really limited because the existing energy consumption probably isn't excessive.
Ask yourself these questions when pursuing credits for maintenance of these historical buildings. Why pay annually for a building built to be around a hundred years or more? How do you get investors' attention for establishing a 100-year management plan? For some facilities, there may be little or no O&M staff assigned to the building.
Response to HVAC problems can be a reactive response, in lieu of proactive response. The idea of pursuing the additional commissioning credit so that the owner has a recommissioning manual may not be considered a wise investment. Instead, the burden of repair, tune-up, replacement, and modernization are passed down to another generation (and their donations). I guess these historic buildings are just going to continue to be sustainable without LEED certification. ES