At KF Builders, we offer three levels of Green design: Standard, Premium, and Platinum. In most cases, the minimum level – Standard – meets ENERGY STAR requirements. Premium and Platinum design levels, in most instances, exceed ENERGY STAR requirements. (Requirements are based on "ENERGY STAR Qualified Homes - Builder Option Package Notes".)

The 2006 International Energy Conservation Code (IECC) identifies three major building climate zones in Arizona: Hot-Dry (e.g., Phoenix), Mixed-Dry (e.g., Prescott), and Cool-Dry (e.g., Flagstaff). For each climate zone, KF Builders follows well-established principles and practices of climatic design. These include:

• Proper building orientation to promote winter solar heat gain and minimize summer solar heat gain (i.e., long-axis of building oriented west-east, when possible).
  
• Shading (including tree shading) for windows and walls exposed to summer sun.
  
• A minimum of two windows (operable) per room (when possible) for natural ventilation (hot climates) and daylighting.
  
• Cool roofs in hot climates.
  
• All ducts and air handlers in conditioned space.
  
• House-wrap for continuous air barrier.
  
• Mechanical ventilation for indoor air quality.
  
• Thermal bypass inspections to insure proper insulation installation.

The goal of climatic design is to minimize the energy demand of your home. This is crucial for “off-grid” (Platinum grade) homes that must supply 100% of their energy requirements using solar electric and solar domestic hot water systems.

Below are specifications for selected building components for homes in hot-dry climates, such as Phoenix. Specifications for other climates may be more or less stringent than those given below. Please contact KF Builders for additional information.

For the Standard home, R-19 fiberglass batts are used in all exterior walls and R-38 unfaced fiberglass batts are applied under roof deck. (ENERGY STAR Qualified Homes require R-13 insulation for exterior walls and R-30 insulation for ceilings in hot-dry climates).

For the Premium home, R-23 blown-in insulation is used in the walls and R-49 unfaced fiberglass batts are applied under the roof deck.

The Platinum home is insulated to the Premium level, plus a 1” urethane coating is applied. If possible, a radiant barrier is installed between the top of the batts and the roof deck.
To insure the proper installation of the insulation, a thermal bypass inspection is conducted before dry wall is installed on all models. Also, upon request, a whole-house air leakage test (a.k.a., “blower door” test) can be performed.

In hot-dry and mixed-dry climates, a top priority is window selection and installation. At KF Builders, all windows for homes built in hot climates are dual pane, low-E, and low-SHGC (Solar Heat Gain Coefficient) to minimize solar heat gain. (In cold climates, where solar heat gain is promoted for winter heating, low-SHGC windows are not installed on south-facing walls).

Windows qualifying for Energy Star rating:

• U-value <= 0.55
  
• SHGC <= 0.35

In the Standard model, aluminum frame windows are installed. Premium level homes use vinyl frame windows, and Platinum homes use wood frame windows. All models meet Energy Star minimum ratings for windows.

To promote natural ventilation, especially in hot climates, KF Builders recommends that windows be operable. Also, we suggest that the window-to-floor area ratio (WFA) not exceed 18% for all homes.

Roofs qualifying for ENERGY STAR rating:

• Low Slope roofs must have an initial solar reflectance of >= 0.65. After 3 years, the solar reflectance must be >= 0.50.
  
• Steep Slope roofs must have an initial solar reflectance of >= 0.25. After 3 years, the solar reflectance must be >= 0.15.

In hot-dry climates, roofs on all models qualify for ENERGY STAR rating. For low slope roofs, KF Builders uses urethane foam and an elastomeric coating on all models. For steep slope roofs on the Standard model, reflective asphalt shingles are installed. For both the Premium and Platinum models, pigmented metal roofs designed to reduce heat gain are installed on steep slope roofs.

Because homes designed and built by KF Builders are air tight, mechanical ventilation is required for indoor air quality. All models incorporate supply-side mechanical ventilation that brings filtered outdoor air into the return plenum of the HVAC system.

For the Premium and Platinum models, an AirCycler programmable ventilation controller is used to provide fresh air on a scheduled cycle. Rather than operating the central system fan continuously, which can waste energy, the recycling control can be set to periodically distribute ventilation air during stagnant periods when there is no call to circulate air for purposes of heating or cooling.

In hot-dry climates, a priority is HVAC sizing and installation. At KF Builders, HVAC equipment and ducts are sized according to the Air Conditioner Contractors of America (ACCA) Manuals J, S, D, and T. For all models, HVAC equipment meets or exceeds ENERGY STAR rating and includes programmable thermostat. (It is recommended that all ducts be tested for leakage using an approved testing protocol).

The Standard model comes with central A/C with SEER > 16 (split system) and electric or gas furnace with AFUE > 90.

The Premium model comes with central A/C with SEER > 20 (split system) and gas furnace with AFUE > 95.

Because the Platinum model is “off-grid”, KF Builders recommends a hybrid cooling system (hot-dry climates) incorporating central A/C equipment with SEER > 20 (split system) and a two-stage evaporative cooler. Because of the high electrical power requirements of conventional A/C equipment, it would operate only during times of high humidity; the evaporative cooler would operate the rest of the time. Evaporative cooling equipment requires about 80% less power to operate than conventional A/C systems, which reduces off-grid solar electric system size and cost. Depending on the size of the solar electric system, backup electrical power (propane) may be required during periods of high humidity.

Residential solar electric systems are either “off grid” or “grid tied”. “Grid tied” systems are the least expensive and require the least maintenance. “Off grid” systems require a storage device, usually lead acid batteries. (KF Builders strongly recommends sealed batteries or so-called “maintenance free” batteries, such as AGM - Absorbed Glass Mat – deep cycle batteries.)

For the Standard model, an electrical stub-out on the roof is provided for any future solar electric system. Also, at least 1000 square feet of south-facing roof is available for systems up to 10 kw.

On the Premium model, we offer a grid-tied system that meets at least 50% of the electrical energy demand.

The Platinum model is intended as an “off-grid” home, requiring a PV system that meets 100% of the electrical load. These systems require storage banks of lead-acid batteries. (The Platinum grade also provides an intermediate design option: a grid-tied system with battery backup. Many people are unaware that, for safety reasons, when there is a temporary shut down of utility power, grid-tied systems shut down, even when the sun is shining!)

Prior to the design of any solar electric system, a detailed electrical energy load calculation is required. Typical daily electrical energy consumption for a home located in the deserts of Arizona can easily exceed 50 kwh, requiring a 10 kw system (such as the one shown above designed by Windsun). A 10 kw grid-tied system (Premium grade) costs about $70,000 before tax credits and utility rebates (see below). A 10 kW off-grid system (Platinum grade) can exceed $100,000 before incentives. Federal and state tax credits, along with utility rebates, are currently running at 55% of initial costs.

The largest load in hot climates is mechanical air-conditioning equipment, accounting for about half of the summer-time electrical energy consumption of a home. Grid-tied systems can be sized for the yearly averaged energy demand. These systems purchase supplemental power from the utility during the summer when demand peaks and sell excess power during the rest of the year. In contrast, off-grid systems must be designed to meet the maximum monthly load in the summer for homes built in cooling dominated climates. Therefore, for off-grid systems located in hot climates, KF Builders strongly recommends strict adherence to climatic design principles (minimize solar heat gain and maximize passive cooling strategies). It may also be possible to use high efficiency evaporative cooling systems, rather than conventional air-conditioning equipment for homes located in the upper Sonoran desert or mixed climates zones at elevations above approximately 3000 feet.

For systems put "into service" between 2009 and 2016, the federal tax credit is 30%. That means that for solar electric systems put into service between Jan 1, 2009 and Dec 31, 2016, you will be able to get back 30% of the total cost of the system, with no cap for residential systems.

In most of Arizona, you can also get a $2.15 per watt rebate from APS or SRP. The federal 30% tax credit is the total cost AFTER the rebate. Just for example, for a 5000 watt system where the total installed cost is $35,000, you would get $10,750 back from APS or SRP, so your cost for the system would be $24,250. You would get a 30% Federal tax rebate and a $1000 Arizona tax rebate on that, so the total cost would be (($24,250 x .70) - $1000) $15,975.

In addition to the above incentives, utilities offer “net metering” whereby the customer is billed for purchases in excess of customer supply or credited for supply in excess of customer purchases (APS-EPR-6). APS requires a bi-directional meter.

To qualify for the utility rebates, the solar electric system must be installed by a licensed contractor (C-11, K-11, L-11).

The most common SDHW systems are active closed-loop systems that use a pump, temperature sensors, and electronic controls to regulate fluid circulation through the collector(s) and heat exchange mechanism. For freeze protection, the heat exchange fluid is either food-grade propylene glycol antifreeze or water in a drainback system. The solar collectors are typically the glazed flat-plate type. These types of SDHW systems are installed on all Premium grade homes.

For off-grid homes (Platinum grade), where electrical energy demand must be kept to a minimum, KF Builders recommends integral collector storage (ICS) or “batch” SDHW systems, since these require no energy-consuming pumps.

Active closed loop SDHW systems require a hot water storage tank, whereas an ICS system can incorporate either a storage tank or a tankless water heater

At a minimum, rough-in plumbing for a future solar hot water system (hot water line stub-out at roof) is included on all Standard homes.

To qualify for tax credits and utility rebates, the SDHW system must be certified as an OG-300 system, which is an engineered system that includes collector, storage and other components integral to the performance of the overall system. The Federal tax credit is 30% of the system cost. APS and SRP rebates are 50 cents per kWh of energy saved based on the OG-300 rating. Typical SDHW systems save 2500 kWh per year and are eligible for an $1250 rebate.

The typical cost of a 2500 kWh system is about $6000, or about $2325 after tax credits and rebates.

In addition, to qualify for incentives an installation must be performed by a licensed contractor with one or more of the following certifications: C-37, C-37R, K-77, K-78, L-77, L-78.

Additional savings in system cost can be realized if low flow shower heads and faucets are installed. Low flow devices lower the hot water demand and thus decrease the required system size.