Performance
Home performance is probably the least understood part of home design, construction and maintenance - even among professionals. All to often, home owners learn about home performance options long after their project is finished because no one speaks with them about performance.
The starting point is asking, “What needs to be measured?”. Home performance used to focus on energy use - reducing energy bills. Terms like “green” and “sustainable” were attached to projects that performed well in terms of energy use yet energy use is only one of the top three things to measure. Here are the three components on which we must focus:
Health
We spend most of our day indoors. Average American spend approximately 90% of our day indoors. That means the indoor environments in which we live have a significant impact on our personal health.
That’s a significant challenge for many of us because we live in older homes that leak air + humidity. Many homes don’t have ventilation so the indoor air quality can be poor - worse than outdoor air.
Poor indoor air quality comes from every-day activities like cooking and cleaning that release chemicals into our indoor air. Poor air quality also comes from common products that release chemical compounds into our air (off gassing). These can cause us to feel lethargic, discourage mobility and irritate underlying health issues.
Comfort
Some homes do not address occupant comfort very well. They have uncomfortable spaces: noticable temperature differences, cold floors, drafts and low (dry) or high (damp) humidity. It’s not just old homes that have these issues. New homes have them too.
Efficiency
The building code and energy code have incrementally improved the efficiency of homes though they can still have issues. The building and energy codes are minimum standards - the worst construction allowed.
It’s not that difficult to coordinate the building systems to work efficiently together, maintain them so they work properly and education occupants so they know how to operate the home and its systems.
Two Systems in Concert
Two systems are key to addressing health, comfort and efficiency: the building enclosure and the HVAC system. HVAC is an acronym for heating, ventilating and air conditioning.
Our goal on any project is to maximize the passive systems (air sealing and insulation) so the house is tight and we have control over the indoor environment. The active systems like HVAC have a high purchase price, operating costs and maintenance costs. We maximize the passive systems to reduce all the costs of the active systems.
We want a good HVAC system. It doesn’t need to be the most efficient or expensive system because it’s tasks are relatively simple: 1) the ventilation system to provides fresh air and exhausts polluted air, 2) the heating/cooling system to provides air filtration, and 3) the cooling system provides humidity control.
How Much is Enough?
How do we determine how much is enough when we’re balancing the passive and active systems? We use a sophisticated tool set to create an energy model of the home. That allows us to test different systems and efficiencies to determine how the project budget is best spent. We can even explore using elements like photovoltaic (“solar”) panels.
The energy model can be used to create a projected rating for the home - a stated expectation of performance. It can be used to show compliance for green building rating systems. It can also be used to show compliance with some building and energy code requirements.
Performance Verification
Performance must be measured during construction to determine if what’s built/installed meets the requirements of the design. Verification includes evaluating the quality of installed insulation, pressure testing the house to determine air leakage levels, pressure testing the heating/cooling system to determine air leakage levels and verifying the HVAC installation meets the design.
This is a critical series of verification points because the opportunities to correct poor work are lost when that work is covered by other work like finishes. We grew our skill set and service offering through additional training/certifications to conduct these verifications rather than leaving them to others.
We have a working relationship with the contractor + her team and we know the design better than anyone. This allows us to work with the project team set expectations and responsibilities so we’re all working toward delivering a predetermined level of performance for your project.
In Conclusion
This has been one of the most difficult pages to craft because there’s so much guidance we want to share so you’ll be empowered to make wise decisions. Here are a few key takeaways before you move onto learning about programming:
Include a stated expectation for performance in your scope of work so the project team understands the target.
We expect to talk you through the levels of performance and help you determine what would be a good fit for your scope of work. Don’t worry if you feel you don’t have all the information you need right now.
Performance does not compete with style. All styles of homes can be high-performance homes.
Don’t leave performance to the end of the design. It’s not easy to add it later because the systems need to be coordinated to be successful and deliver the most meaningful impact on the health, comfort and efficiency of your home.
Thanks for learning about performance.
The next step in this series is learning about the program.
This is the second page in a series of four pages: