It’s easy to get all excited about the idea of building a net zero energy house.
The benefits are big, including low monthly utility bills, comfort and good karma for doing the right thing by the planet. It’s also easy to see it through rose colored glasses. In the interest of getting the bubble bursting out of the way, I’m here to tell you that NO construction project is easy or breezy and building a net-zero energy home is DIFFERENT. It’s not more difficult, it’s just different.
If you look back at my previous article on building a net-zero energy home you will see that I recommend two approaches for building a net-zero energy home. The first is for existing homes. In a nutshell, do what you can to reduce the energy use of your home. Air sealing and insulation are the key ingredients here. Then, add a bunch (yes, it’s usually a BUNCH) of solar panels to get to zero.
The option I recommend for new construction is to reduce the energy loads first via high performance construction and then add solar panels (usually a lot less than the BUNCH for an existing house).
Planning to build a new home and want to go net-zero via high performance?
As I mentioned, high performance net-zero energy construction is different. Different means that most contractors will look at you as though you are just this side of nuts. It means your friends will probably think it’s cool, but secretly wonder if you are going over the deep end. If you are willing to travel the road less traveled, then building a high-performance net-zero energy might be right for you.
The strategies to get to net-zero include renewable energy sources, air sealing, minimizing thermal pathways and proper insulation and ventilation. These are the things that set a high performance net-zero energy home apart from standard construction. These strategies sound a little odd, but the thing is that the trades, products and skills required to build such a home are all mainstream and available in the US. Believe me, this is huge!
What are the differences between the two approaches?
- It will typically take more time to get the air sealing done right
- It will typically take more time to insulate properly (yes, you can screw up insulation)
- It will typically take more time to frame an efficient house
The three items above assume your contractor doesn’t have experience air sealing, getting the insulation right or if you are framing, the experience using advanced framing techniques. Typically, contractors have the skill to do it, but it isn’t business as usual so it takes extra time. If you can find a contractor who has figured this stuff out, hire them!
The Building Shell
The building shell is thicker to hold more insulation and tighter to keep the precious air that you pay to heat and cool inside and not leaking to the exterior.
Run of the mill doors and windows are leaky and poorly insulated and could be a liability in an otherwise well insulated and air tight home. Buying the best doors and windows you can afford is well worth it.
High performance houses get their fresh air mechanically instead of through all the leaks in the house. There is a special piece of equipment for this called an HRV (heat recovery ventilator) or ERV (energy recovery ventilator). For most contractors this is new and different. It requires all the same skills and tools to install as a ducted system, but it is different. Anything different takes time, and time is money.
Nothing particularly different except that cold and hot water lines are insulated. Typically, hot water lines might be insulated, but the reason to insulate a cold water line is to prevent condensation.
A net-zero energy home might have a solar hot water heater or a hybrid hot water heater, or depending on the size of a home an instant hot water heater. Again, all mainstream, but a little different.
Testing and commissioning
This is a big difference and an added expense not normally seen on a construction project. Making sure the home performs as designed is a critical ingredient to the success of the process. During construction, a blower door and thermal imaging test will need to be performed to verify that the house is air sealed and insulated properly. Once construction is complete, commissioning (fancy word for testing) to verify that everything is installed properly and functioning is your ticket to peace of mind. Testing and commissioning is best if done by a third party to avoid a conflict of interest. HERS raters are typically the team member to provide the required testing and commissioning.
The above items are time and money items. No lie, it does cost more to build this way. However, savings are realized each month in reduced utility bills. The next two items don’t cost anything, but do require common sense.
Locating the majority of the glass on the south and of course the solar panels on the south is the way to get free heat and electricity. Duh, but it’s surprising how often this basic thing is missed.
Living in it WELL
This is probably the most important thing that no one talks about. When it’s all said and done, it is important to understand how to operate the house because it is actually possible to live in a high performance house and be an energy pig! Don’t be a porker is all I can say. Program your thermostat and don’t leave the lights or ceiling fan on when you leave the room, and don’t leave the front door open when the heat or air conditioning is on! Things like that make all the difference. Check out my no-brainer tips for saving energy to find out more.
Building a high performance net-zero energy house is different, but really, it’s not more difficult. It will take more time and money typically because there is a learning curve and some of the materials like better doors, windows and extra insulation actually do cost more. It also requires a dose of common sense to achieve net-zero energy. The benefits are long term and if you are still excited about high performance net-zero energy construction (as I am), even after I have attempted to rip off the rose colored glasses, then maybe, just maybe it is how you should build your new home. (I hope so).
If you know someone who would enjoy this article, please share. I appreciate it and thank YOU in advance.