Mechanical Systems

What exactly are mechanical systems?

That's a technical-sounding phrase for many of the things that we use every day in our homes and buildings. Some examples of modern mechanical systems include power, lighting, heating, ventilation, air conditioning, fire and smoke detectors, life safety, plumbing, elevators, and sprinkler systems. When upgrading and/or installing these modern mechanical systems in older buildings, preservation architects are tasked with finding ways to fit (and then hide) a tremendous amount of duct work and wiring to actually operate the new systems – none of which were considered for buildings designed prior to World War II. Factor in the need to always protect the bones and historic fabric of a home or building, and this task becomes even more complicated. 

However, integrating new systems is not just a matter of finding a place for all of the parts; you must also be mindful of how altering the interior climate will affect the performance of a building's original (and often historic) materials. When the differential between inside and outside temperature is altered greatly, the risk of damage also improves greatly. Too much or too little humidity can have adverse effects on structural as well as decorative elements, rotting wood, dampening insulating, and corroding metal components.

At the core of the issue of retrofitting historic buildings with upgraded mechanical systems is human comfort and health. It is not an unreasonable expectation that we should feel comfortable with the air temperature and quality in our homes, especially when technology exists to make this possible. Furthermore, mechanical codes establish minimum requirements for fresh air, comfort conditions, and energy efficiency. In older and historic buildings, one aspect of rehabilitation projects for energy efficiency and improved performance (as well as comfort) is understanding how the building was intended to function with operable windows and other passive ventilation systems.

Similar to other weatherization tactics for your home, there is no one-size-fits-all solution for upgrading mechanical systems in your older or historic building. Instead, we recommend a more holistic approach – one that is specific to your home or building, its use, and the needs of its occupants. We also recommend considering a combination of solutions and/or systems. Since we treat each building individually, it might be necessary to think of it as several systems working together, instead of one system meeting all of the requirements of the building's users.

The following frequently asked questions are intended to further explain the passive or "built-in" systems of older and historic homes, as well as the many options that exist for upgrading older structures with modern technology.

Are there options for energy efficient heating and cooling systems in older and historic homes?

Yes, recent advancements in these systems have created options that may be compatible with your older or historic home.

Although this is a topic that you should definitely discuss with a well-qualified consultant, there are now several high efficiency gas furnaces, boilers, and central air conditioning systems on the market to choose from.

Traditionally, architectural styles and their features were a reflection of their region and climate. Houses were sited and built where occupants could receive the warmth of the sun during the winter and cool breezes through the house in the summer. Houses were also constructed near large trees for cooling and shade, and water for convenience. Homes built in the south, where summers are hot and humid, required porches and shutters on the windows, as well as plenty of design for air circulation. In the southwest United States, houses were (and still are) built in an adobe style with thick walls to keep the inside temperatures cool.

These methods have not changed dramatically over the years, and if you live in one of these older homes, you have probably noticed the details that make your building function according to the climate. It's how you, the occupant, choose to make use of these systems that makes the difference. Most importantly though, a homeowner in the southwest should not be taking the same approach to upgrading the systems in their building as a homeowner in the northeast; each building should be treated individually.

My older home is hot during the summer and cool during the winter. What can I do?

First and foremost, remember that your older home probably has several "built-in" features to help combat the elements. Are you maximizing them?

Older and historic buildings without modern mechanical systems were designed with human comfort in mind, relying on building features operated by the occupant to keep the environment comfortable. Doors and windows were meant to be opened or closed to allow for cross ventilation. Along the same lines, shutters and awnings were meant to be opened or drawn for sunlight or shading.

That being said, it's important to know what your goals are to decide which course of action is best for you and your building. Is your goal to lower your energy bills? Do you want to improve your comfort during hot and cold months? Is it all of the above? As mentioned before, your older or historic building is going to operate differently than a modern building, so you should take deliberate steps to improve conditions.

Passive Heating and Cooling Measures

The way a building is used, in conjunction with the inherent qualities of its materials and construction, plays a large part in its energy efficiency. This should definitely be considered when making decisions to improve its conditions and performance. Passive measures can be described as energy-saving techniques in a building that do not require alterations or new systems. Here are some examples of passive energy-saving techniques:

  • Lowering the thermostat in the winter, raising it in the summer, and using a programmable thermostat.
  • Controlling the temperature in rooms that are used and establishing climate zones throughout the building with separate controls so that unused rooms are unconditioned.
  • Reducing the number of lights used, maximizing natural light, and switching light bulbs to energy saving compact fluorescent bulbs.
  • Using operable windows, shutters, awnings, and vents as originally intended to control the interior environment.
  • Cleaning radiators and forced air registers to ensure proper operation.
  • Having your furnace and boiler cleaned and serviced.
  • Making sure ducts and pipes are well insulated.
  • Offsetting the use of electricity with the purchase of renewable energy (such as wind energy) through your local energy provider. For example, Pennsylvania's energy provider has a program that allows customers to pay an additional fee (as low as $3.00 a month) to help fund wind farms. In turn, this increases the amount of wind energy delivered to the electrical grid while reducing the need for energy from other sources.
  • Monitoring occupant behavior with regards to energy.
  • Metering energy use.

Active Heating and Cooling Measures

While passive measures allow homeowners to make upgrades through do-it-yourself improvements, active measures are definitely the opposite. This is where we highly recommend consulting a preservation professional, as these invasive alterations to an older or historic building must be handled with care. The steps we recommend are as follows:

  • Determine the use of the building.
  • Assemble a qualified team of experts.
  • Have a professional do a conditions assessment of the existing building and its systems as well as a feasibility study.
  • Prioritize the architecturally significant spaces, finishes, and features to be preserved.
  • Make sure that you or your consultant is familiar with local building code. Determine how they can be met while maintaining the historic character of the building.
  • Evaluate all of the system options for your building, but resist the urge to over design and add unnecessary systems. This could be detrimental, both financially and to the functionality of the new system(s).

Some systems, projects, and issues that you should discuss with your consultant are:

  • New boilers and circulating pumps, reconditioning historic radiators, and fan coil units.
  • Basic HVAC and heat pump systems.
  • Combined air and water systems that combine pipe and duct systems, therefore allowing for greater flexibility in installation.
  • Portable fans, dehumidifiers, and heaters.
  • Unused fireplaces and closets that can be converted to ductwork and electrical boards.
  • Find out if your building has cavity walls, which are good places to hide wiring. False floors can also hide mechanical and electrical systems. 
  • If air conditioning units are put on the roof, they need to be placed so that they are not visible.