Q:“Green” has become the marketing buzzword. What’s really important for remodelers to know?

A: Green starts with applied building science and building performance. Building science leads to improved health and safety, comfort, building durability, and energy efficiency. The home is a system. Changes in one part of the system can and often will affect other parts.

One such building science issue is combustion safety in the home. For example, if you have an old-fashioned water heater with a flue going up the chimney, what happens when you tighten up the house?

With a flue, cold air in the house pushes warm air up the chimney. If there’s not enough pressure in the house to do that, combustion gases will be brought back into the house. Those gases include a large amount of water vapor, potential carbon monoxide, and potentially harmful combustion by-products — things you don’t want the home’s inhabitants to breathe.

Existing homes and most new homes have many air leaks. There are cases where the house is tightened up and the family ends up in the hospital that same night.

Remodelers need to learn about these things. We always recommend that people who do envelope work be certified by the Building Performance Institute — at least as consultants. Heating contractors should be certified by BPI, North American Technical Excellence, or the National Comfort Institute.

At least three rules just don’t apply anymore: “My father did it this way”; “I’ve been doing it this way for years and nothing happened”; and “Everybody does it this way.”

—Edward R. Voytovich is executive director of Building Performance Contractors Association of New York State, www.home-performance.org.