How Solluna does it

Here are some of the tools and components Solluna uses to build a sustainable home.


In Texas, it’s about the summer sun.  Ideally, you want to orient your home so the long exposures face north and south, minimizing sun exposure on east and west sides.


Of course, in an urban setting, you can’t always choose which way your home will face, but 2-foot or more overhangs will shade your windows in summer.  During design, we minimize the windows on east and west sides, add porches for protection on southerly exposures, and use other tricks to shade and protect from sun exposure.


Windows can have a huge impact on your utility bills.  In our hot-humid climate, high-performance windows keep the heat outside where it belongs. Properly placed and sized, windows allow light into your house (reducing your electrical lighting load), allow for breezes to cool your home, and allow for passive solar heating during the winter when the sun is in a lower path.


When framing the house, we’re thinking ahead to energy efficiency.  Since wood is a poor insulator, we use “advanced framing” techniques that use less material and leave more room for insulation.  Engineered wood products, where they’re appropriate, save material, time, and costs.  We have used all kinds of alternative framing techniques, such as SIPs (structural insulated panels) and ICF (insulated concrete forms); these techniques have a place given the right design, situation, and budget.


The goal is to keep moisture out of your home, keeping in mind that when it does rain in central Texas, it sometimes comes in torrents.  We favor an exterior sheathing material that has a built-in moisture barrier, and we obsessively seal up every crevice, nook, and cranny.


A standing-seam metal roof is perfect for central Texas.  It keeps the house cooler because it reflects the sun’s infrared light, reducing heat absorption into your home by as much as 36%. A metal roof is maintenance-free and will last the lifetime of the house. A metal roof is the right way to go if you’re planning to add solar panels or a rainwater harvesting system.


Solluna uses spray foam insulation.  It’s effective in air sealing and insulating because it’s applied as a liquid and expands multiple times its original liquid size in seconds. As it expands, it conforms and fills cavities and voids to create a sealed thermal envelope. Spray foam insulation creates a highly-effective seal against air infiltration, the number one source of energy loss in a structure. This insulation adheres to any clean, dry surface and will not sag or settle. Combined with other building components, spray foam insulation can reduce your heating and cooling bills by up to 50% — a worthwhile investment!


Feeling comfortable depends on a complicated mix of factors—not just the temperature of the air, but also the relative humidity, the rate of air movement, and the temperature of the materials around us. The passive design of your home and the materials and techniques we use to build it go a long way toward keeping you comfortable.

And then there’s the Texas summer heat.  n a typical home in our climate, air conditioning is the #1 energy cost. Because we’ve created a continuous, sealed thermal envelope around your home, we can save you money by reducing the required size of the HVAC (heating and air conditioning) system. The high-efficiency system will be “right-sized” to fit, giving you lower utility bills. Return air ducts in each room plus ceiling fans help with efficiency and comfort, too.


A solar photovoltaic system can be an essential component of a renewable energy system if you’re aiming for a zero-energy home – a home that generates as much energy as it uses. While many Solluna home owners are willing to make the investment, it’s not a prerequisite for a green home.  Most of our clients who do install a solar PV system choose a system that ties into the electrical grid, which means electricity flows both ways. Many utility companies will buy back excess electricity that your system uses, and some provide rebates and incentives to help you offset the cost of the system.  When your panels are generating more electricity than you need, it’s fed back to the grid and your meter runs backward.  When it’s dark and your panels aren’t generating electricity, then your house pulls electricity from the grid.


Sure, we all know about conserving water by using high-efficiency toilets and low-flow faucets and showerheads, plus water-efficient appliances – dishwashers, water heaters, and washing machines.  But how many times have you stood in the master bathroom waiting for hot water to arrive?  We forestall water waste by designing efficient plumbing runs.  You can’t just leave this part to chance.


Water heating is a big deal.  In typical home, heating water is the 2nd biggest energy expense, anywhere from 15 to 30% of the home’s total energy bill!  You need an efficient water heater, and you don’t want to waste hot water with long plumbing runs from the water heater to kitchen and bathrooms. What’s the best water heating answer? It depends on your home, so proper planning is the key. There are some terrific new efficient water heaters and solar water heaters available on the market which, combined with properly insulated pipes and the right hot water re-circulation system, can save you a bundle on your utility bills.


A rainwater harvesting system has many benefits.  We can install a rainwater harvesting system that supplies all the water needs for your home.  Or, you can choose a smaller system to irrigate the landscape.


For energy efficiency, your home is built to be tight and free of leaks. Now let’s make sure the indoor air quality is healthy. We start by using paints, adhesives, and building materials with no volatile organic compounds (VOCs).  Proper ventilation keeps excess moisture out of your home. An air-intake system on the HVAC system will inject fresh air into your house and, of course, the house is designed with air-flow in mind in the placement of windows and doors.


Appropriate landscaping can protect your home by channeling cooling breezes and providing shade. Using easy-care, low-water native plants, you can cut your maintenance labor and water use. And of course, with a rain water harvesting system, you can water the landscape with your captured rain water.


Solluna is serious about using resources wisely. Our construction jobs are planned to minimize waste. We sort and recycle a majority of construction waste materials, and we champion the use of recycled and reclaimed materials and components. You’ll appreciate the care our crews take to minimize the impact on the landscape and the neighborhood.


Don’t just take our word for it. After your home is built, a third-party tester performs three tests to measure how well your home performs:  duct leakage test, safety back-draft test, and blower door test.


When construction is complete, having your green home rated gives you a scorecard to measure how well your home stacks up. Solluna Builders is a long-time participant in Austin Energy Green Building. A typical Solluna home earns 5 stars, the highest rating.