Expertise
Building Science Education
Building science is simply the study of how heat, air, and moisture move through a house. A buyer who understands the basics can evaluate a builder's specification in minutes.
- ACH
- Blower door testing
- Indoor air quality
- Energy efficiency
- Attic systems
ACH and what the number means
Air changes per hour at 50 pascals (ACH50) measures how leaky a home is under test pressure. Lower is tighter. Codes commonly require 3 to 5 ACH50; high-performance builders test well below that.
Ask for the tested result on a home the builder has already delivered in your community, not the target.
Blower door testing
A calibrated fan depressurizes the house and measures the airflow needed to hold the pressure. It converts leakage from an opinion into a number, and it is how the ACH50 figure is produced.
Indoor air quality
Tighter homes retain whatever is generated inside them. Good outcomes come from source control (low-emission materials, sealed combustion, vented range hood), filtration (MERV 13 where the equipment allows), and deliberate fresh-air ventilation.
Attic systems and the thermal boundary
The most common performance failure in production housing is ductwork in a vented attic, outside the insulated boundary. Options that fix it are conditioned attics, ducts in dropped soffits, or a sealed and buried duct assembly.
Frequently Asked
What is a good ACH50 for a new home?+
Around 3 ACH50 meets common code targets. Below 2 is genuinely tight and generally requires mechanical ventilation to be designed in.
Can a house be too tight?+
Only if it is not ventilated. Tight plus ventilated is the goal: control the air you bring in rather than letting the building leak randomly.
Is a conditioned attic worth the upgrade?+
In hot climates with attic ductwork, it is one of the highest-value envelope decisions available at the design stage.