We start the new year with a report that places people at the top of home design considerations. In today’s high performance homes, occupant energy usage is often more important than climate-related energy usage. Building an exceptional home that exceeds occupant expectations and minimizes callbacks requires designing homes for exceptional people!
Our report analyzes field data and applies “3 sigma” design to determine fresh air ventilation and comfort conditioning needs that satisfy most people. The answers are simple:
1) Each home, regardless of size, should have fresh air ventilation air flow capability of 300cfm
2) Each home, regardless of climate, should have 2 to 3kW (1/2 to 1 ton) of heating and cooling capacity
Design methods that assume average people lead to poor indoor air quality, discomfort, and dissatisfaction. Average people, like average weather and average height, rarely exist. There are people taller than average and people shorter than average, but there are very, very few people at any instant of time who are average.
Meeting the needs of most people is discussed in terms of doorway height. Any home builder constructing doors with average human height (5’7”) will have many complaints and few customers. Interestingly, even though the shorter half of the populace should be satisfied with average doorway height, more than half of the homes will be dissatisfied. Our simple analysis of doorway height explains why 3 sigma design, which meets the needs of 99.7% of the general populace, is reasonable. The average North American doorway is 6’8”, which covers 3 sigma of the populace, demonstrates this principle.
If you’re adding 1 ton of comfort conditioning capacity to meet dynamic human and climate conditioning loads, consider adding 2 tons instead and increase your home’s comfort conditioning efficiency 20 to 30%. We have previously discussed how today’s high performance, ductless minisplit heat pumps have increased efficiency when operating at part load capacity (see our Minisplit Mania report from June 2018). Two, independent (not “multi-head”) minisplit heat pumps operating at partial capacity are more efficient than a single heat pump operating at high capacity! We discuss this important characteristic in our new report, with additional laboratory data we’ve collected to show the same efficiency increases occurs in ducted minisplits, too. In addition to increased efficiency, comfort conditioning is improved, and comfort system redundancy gained, making your homes even more exceptional!
