Older buildings carry a lot: original windows and plaster, a neighborhood's history, and decades of people who lived, worked, and learned inside them. They also tend to leak air and waste energy. The good news is that you don't have to choose between character and efficiency.
Here are seven ways to make an older building more efficient while respecting what makes it worth keeping.
Before installing new equipment, find out how the existing systems are actually running. Leaks, dirty filters, disabled sensors, faulty wiring, and gaps in how staff operate and maintain equipment all drive up costs. An audit can find problems in each of these areas, including water systems, where leaks and inefficient operation waste both water and energy.
Original windows carry much of an older building's character. They were often custom fit, and replacing them can mean changing the size and shape of the openings. New windows also take energy and resources to make, ship, and install, and the old ones have to go somewhere.
The trade-off is that old windows usually don't perform well. Storm windows, weather stripping, and caulking can stop drafts, and cellular or insulating shades can cut heat loss through the glass.
Windows aren't the only place air gets in and out. Leaks raise heating costs in winter and cooling costs in summer, and they let moisture collect inside the building, where it can cause damage. Common spots to seal include the tops and bottoms of exterior walls, cracks at the base of walls and around windows and doors, recessed light fixtures, and where walls meet the attic.
There are many ways to make an HVAC system more efficient: using natural ventilation and heat sources, reducing losses in conventional systems, adding thermal storage or free cooling, and using sensors and automation to keep systems running at their best.
In an older building, the challenge is fitting new systems in without spoiling the space. Ductwork needs careful routing and concealment to preserve the building's look while meeting code and comfort requirements. Fan coil units often replace radiators in historic buildings because their piping is smaller and less intrusive than forced-air ductwork. Where there's little or no space above a vaulted ceiling, vertical duct routing can help preserve it.
Whatever the approach, the goal is to place equipment where it's hidden from view or fits the character of the building.
Heat loss and gain are typically greatest at the roof, and older roofs may need structural upgrades alongside new insulation. Insulating an unfinished attic is usually simple, saves energy, and causes little disruption to historic features.
If the basement is inside the building's thermal envelope, meaning the HVAC system heats and cools it, insulating its floors, walls, and vents reduces energy use and helps manage moisture. If it's outside the envelope, insulating between the floor joists under the subfloor is generally recommended.
Wall insulation can improve efficiency but risks damaging historic features. Blown-in insulation in wall cavities is the least invasive option. Tackle it only after the roof and basement are done, and only if an analysis shows it's cost-effective.
Beyond the HVAC system, other equipment offers savings too. High-efficiency water heaters use much less energy than older models, and tankless or solar water heaters can save even more. Replacing older refrigerators, dishwashers, washing machines, and other appliances with efficient models lowers electricity use and can ease the load on the cooling system.
Solar and geothermal can add clean energy with minimal changes to a building's look and structure. Pursue them after the other upgrades, once an analysis confirms they're cost-effective.
Solar panels can go where they're hard to see, such as low on a flat roof or on a secondary roof slope. Solar thermal collectors heat water, and photovoltaic panels make electricity.
Geothermal systems use the earth as their heat source. Compared with conventional HVAC, they can take up less equipment space, run more quietly, and lower energy use, emissions, and long-term costs.
Every older building is different. Start with the audit, finish with renewables, and let what you learn guide everything in between. Our engineers can help you find the right path for yours.