While we know that zero energy homes are within reach of anyone who has the resources to build a new home, there are many people who feel that they just aren’t ready to go that far. For these folks, zero energy READY (ZER) homes are a great answer. According to a 2018 study by the Rocky Mountain Institute, the additional upfront cost of a ZER home is anywhere from zero to three percent. A ZER home has all the efficiency, health, and durability advantages of a full zero energy home. They are prepared for solar panels, but to save on initial costs they are not yet installed. ZER is a big step in the right direction when finances are tight or it just isn’t time to dive into the solar aspect of the project. When the time is right, solar can be added to the home to make it fully zero energy and even have enough left over to power an electric vehicle with proper planning.

Whether you are the builder, the designer, or the home buyer, a little bit of thoughtful foresight can make any home design a zero energy ready home. It is best to plan for the zero energy features at the very start of the design phase – and be sure to involve the builder, designer, home buyer, and key subcontractors at this time.

In a previous post, we discuss the 12 Steps to Affordable Zero Energy Homes. In it we describe many design concepts and construction practices applicable to zero energy ready homes. The first eleven steps describe how to design a high-performance building envelope with high-efficiency appliances, ventilation, and heating and cooling equipment. These steps represent a menu of choices rather than a strict recipe. Some steps can be emphasized more than others. Within each step, there are several alternatives. By conducting an energy model, you will discover which measures are most important and how you can tailor the final package of energy-efficiency measures to your climate, market conditions, and financial resources. The final step is to plan so that solar panels can easily be installed at a later date.

Here are a few tips to make your ZER home planning more successful.

  • Learn about the design elements and construction practices that will increase efficiency and even reduce overall cost.
  • Use energy modeling to determine how much energy your home will use annually. This will help your solar contractor decide how many panels you’ll need and if your roof has enough space and proper solar orientation.
  • Involve your solar contractor during the design process to be sure that your solar ready plan is comprehensive.
  • Participate in an energy efficiency or green building certification program that emphasizes zero energy construction. These programs offer a clear efficiency goal and technical assistance. Most programs include energy modeling and air leakage testing to support your effort.
  • Be sure the roof structure is designed to support solar panels. Although panels are very light, they must be anchored securely against uplift caused by heavy winds. With most new home construction this should not be a problem, but it is worth double checking with the designer or structural engineer.
  • To help reduce carbon emissions and to become truly net zero, consider designing your home to use electricity for everything. This will require an electric service panel with a capacity of at least 200 amps for a typical home.
  • Orient the building to the south when possible. If sun hits the south wall of the home on the shorter days of winter, you’ll get free heat.
  • Identify a roof slope for the solar panels. It should face either south or west. The direction you choose could depend on the best fit for your electric utility. While a due south orientation will generate the most energy overall, the output is greatest at midday. Some utilities have a glut of power at that time of day and encourage west-facing rooftop solar panels that create more power later in the day.
  • Contact the electric utility for their roof orientation recommendation, their interconnection requirements, and details about their financial incentives.
  • Design the home so that the roof slope designated for future solar panels has as few obstructions as possible. Keep that roof clear of all plumbing vents, overhead power lines, dormers, and any other objects that might limit the placement of solar panels or cast shadows on them. If shading the panels is unavoidable, plan on using micro-inverters that allow individual panels to continue generation even if other panels in the array are shaded. They are also useful if some of your panels face one direction, while others face a different direction.
  • Allow additional space near the main electrical service panel for the future power inverter, solar electric meter and other equipment required by the solar contractor. You may decide on storage batteries and an electric vehicle charger in the future, so make sure you have ample wall space for all these devices.
  • With your solar contractor’s input, run an electrical conduit from the location you’ve identified for the inverter and batteries to a roof location that is convenient for making the connection to solar panels. Most solar contractors like to end the conduit within an attic space to allow some flexibility on where it will later penetrate the roof. Some builders choose to hold off on the conduit with plans to route it up the outside surface of the wall on its way to the roof. In any case, you should have a plan for where and how the wiring will run.

Experience and planning will reduce construction complications and costs. To find design and construction professionals with zero energy experience consult the Zero Energy Project’s Directories. They will have the knowledge and experience for planning and implementing a successful project, while saving time and money. Good design and planning is the most cost-effective path to a zero energy ready home.