Monday, August 29, 2016

Calling all architects! Help us recover from “Pointy Roof Disease”

Ok, this post is from the perspective of a rooftop solar energy advocate, but hopefully it will spark some serious discussion and eventually design changes!

Let’s take a look at what has become of roof designs of new homes in North Texas. Let’s take a look at solar PV technology. And, let’s take a look at the recent “solar-ready” provision in the optional section of the 2015 International Residential Codes. Ultimately, we need help from architects to develop innovative ways to couple new roof designs with solar-ready features to help North Texans on their path to “net zero” homes.

First, what is “solar-ready”? A new solar-ready home is designed and built to prepare for the most efficient use of solar PV (photovoltaic) energy panels in the future. Homeowners have the choice of installing the panels immediately after construction, or waiting to exercise this option at another time. There are several factors that make a home solar-ready:

  • installation of appropriate electrical systems
  • adequate south-facing roof space
  • angle of the roof to the position of the sun

Specific details are available in Solar Ready Provisions, Appendix U of the 2015 International Residential Codes. Building a solar-ready home saves time and money. It enables a homeowner with an energy efficient home a future path to “Net Zero”. This means its solar PV system generates enough electricity during the year to offset all or nearly all of the home’s electricity consumption for the year.

According to Wikipedia - A roof is part of a building envelope. It is the covering on the uppermost part of a building or shelter which provides protection from animals and weather, notably rain or snow, but also heat, wind and sunlight.

One of the great things about rooftop solar PV is that it can leverage the normally unused space of a home’s roof. It can allow the roof to serve its normal function as described above, and a second valuable function to capture light energy from the sun to help power our home’s electricity needs.

Now here is the rub. For whatever reason when it comes to roof designs, it seems that the one with the most points and angles wins. Over time, it seems a bit like the spreading of “Pointy Roof Disease”. All these angles and all these points, especially when placed on the south facing roof, make it very difficult, if not impossible to have a solar-ready home.

Take a look at the following photos of North Texas roofs. Ask yourself, what is the purpose of the angles/points? What is the function?

Fig 1 – Three main roof surfaces. For a south facing roof surface, having just one main surface would greatly facilitate cleaner installation of solar PV.

Fig 2 – Five (or six) roof surfaces. Reducing this to maybe two surfaces would greatly facilitate cleaner installation of solar PV.

And these that follow seem to be competing to win the prize for the MOST points and angles. If these represent the south facing roof surfaces, then these roof designs virtually eliminate the potential for a productive rooftop solar PV installation.

I wonder - what is the function of this “extra” triangle protrusion on this roof?

And what is the function of this double peak with the trough that would be a great place for roof leaks to form?

So which of these do you think wins the prize for the MOST points and angles? And which one has any chance of installing rooftop solar PV in the future and achieving net zero? Sadly, these roof designs are severely limiting the future potential of net zero homes.

The goal of this blog post is to raise awareness and start a dialog to promote solar-ready home designs! Share it with your friends. Reach out to encourage architects to begin providing creative solutions and tackling the transition to solar-ready home designs. Tell homebuilders that you want to buy homes that are solar-ready! North Texas uses more electricity per residence than any other part of the state. Combining new energy efficient home designs with solar-ready home designs creates a sustainable path to the use of clean local distributed energy and reducing the strain on our electric grid for all of us!

Calling all architects! Help us recover from “Pointy Roof Disease”! Bring on the age of solar-ready homes! Comments welcome and encouraged!

Shine On!
Plano Solar Advocate (LH)

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