Can I Retrofit My Historic Home with an HVAC System?

Yes, you can retrofit a historic home with an energy efficient HVAC system. If you tour some of Portland’s popular historic homes, you’ll find that many have one thing in common—retrofitted HVAC systems. This is good news if you wish to retrofit your historic home with a modern, efficient HVAC system while preserving its charm. While the installation of an HVAC system is possible, it will take an HVAC expert’s ingenuity and creativity to complete the complex project with minimal alterations to the home’s appearance.

Challenges of Installing an HVAC System in a Historic Home

• The municipality may have limitations regarding alterations if you wish to maintain the home’s historic status.
• The home doesn’t have the space to accommodate ductwork without lowering ceilings.
• Existing ductwork might not be the right size.
• You may need to strip interior finishes or exterior cladding to install insulation and vapor barriers.
• The home might not be able to withstand the vibrations caused by HVAC equipment.
• The home’s electrical system may not accommodate the HVAC system’s load.
• The location of registers, grilles and other HVAC equipment requires thoughtful placement to preserve historic finishes and features.
• Retrofitting may involve taking steps to tighten the building’s envelope, such as the installation of high-efficiency window units, to prevent energy losses.
• You may need to monitor ambient conditions frequently to determine if the HVAC system creates conditions that promote the cracking of wood or finishes, metal corrosion, rot, paint blistering and other problems.

Planning the New HVAC System

Before installing a new HVAC system in a historic or older home, you must determine how you will use the building to choose the best heating and cooling options. Will you live in the home or open it up to the public as a museum or retail space? Will you use the home constantly or for seasonal events? In general, the best uses for a historic building are those that require the least amount of modifications to its major architectural features.

After determining how you’ll use the home, you may need to hire a team that consists of an HVAC design expert, and HVAC installation expert, preservation architect, mechanical, electrical and structural engineers, and a preservation consultant. The individuals in this team should be familiar with:

• Preserving historic architecture
• Tenant requirements
• The home’s heating and cooling load
• How an HVAC system will affect the home
• Building and fire codes
• The home’s existing construction materials and mechanical systems
• How to improve the home’s energy efficiency

Depending on your situation, these experts might suggest that you measure interior humidity and temperature levels for a year using a hygrothermograph, as the conditions current conditions are the ones that preserved the home for decades.

When you work with your team, it is a good idea to prioritize the spaces, features and finishes that you wish to preserve. Then identify spaces that are more appropriate for mechanical equipment, such as attics, basements, false ceilings, floor cavities, closets, vertical chases and stair towers.

HVAC Solutions for Historic Homes

Mini-Split System

Mini-split systems are similar to furnace and air conditioner combinations in that they have indoor and outdoor units. This type of system, however, doesn’t require as much ductwork, so you can condition the air in rooms that can’t accommodate ductwork. The installation of mini-split systems is simpler than traditional systems, is minimally invasive and allows for targeted zoning, so you can control the conditions in different areas of the home.

High-Velocity System

A high-velocity air conditioner is great for older homes that don’t have existing ductwork. This type of system uses small tubes that a professional snakes through and around existing construction, such as closets, above ceilings and in crawlspaces. This solution requires little retrofitting and the registers are unobtrusive.

Modulating-Condensing Gas Boiler System

A boiler system is a comfort system found in many historic homes. In it, a pump circulates heated water through radiators and pipes before returning it to the boiler. While there a few different types of boilers, the most effective tends to be a condensing boiler, which uses a second heat exchanger to produce more heat, making it more efficient.

Central Air Conditioning System

If a historic home has considerable attic space and basement or crawl space, a central air conditioning system with floor or ceiling registers in each room might be appropriate.

When considering the installation of an HVAC system in your home, gather ideas by visiting similar historic homes in your area. Talk to the homeowners or the maintenance managers (if the home is open to the public) and seek tips about overcoming the challenges that come with installing modern equipment in older homes. Then get in touch with the experts at AAA Heating and Cooling to get the process started.