Install a plumbing and wiring chase from the utility room to the roof space designated for the future solar hot water array Space requirements and layout for solar water heating and photovoltaic system components should be taken into account early in the design process.
See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Single-Family New Homes, and Indoor airPLUS.
A renewable energy-ready home (RERH) is one that is built with the wiring and plumbing conduit and other components in place to facilitate the future installation of solar photovoltaic panels and/or solar water heating panels. Some energy-efficiency programs, like the U.S. Department of Energy’s DOE Zero Energy Ready Home Program, require homes to be renewable-energy ready.
To meet the requirements of the DOE Zero Energy Ready Home program, install either a single 4” or two 2” PVC chases from the utility room to the roof space (see Figure 1). The pipe chase should be installed as a straight run and be clearly labeled as an RERH component.
A single straight 4” pipe chase or two 2” pipe chases installed in a straight run from the utility room to the underside, or attic side, of the designated solar array roof area will allow for the installation of the solar pipes and pipe insulation during the solar system installation. The pipe chase can be made of lightweight PVC or any other code-compliant material that is favored in the local housing market. It is not recommended to use a boxed-in open chase in the wall as other contractors may inadvertently install wires, plumbing, and ductwork through it. The use of a boxed-in open chase may also compromise the integrity of the home’s thermal shell. With this in mind, the chase should be capped on both ends and sealed at all floor and ceiling penetrations to maintain air tightness and mandatory fire ratings.
A straight pipe chase between the utility room and the attic is the recommended method. Minor horizontal pipe runs at either end of the pipe chase are allowable. However, in situations where the pipe chase between the attic space and the utility room travels at a slope, bends, or terminates in an area lacking sufficient access or in a way that would prevent the continuation of the pipe run to the collector area or solar storage tank, it is recommended that the actual system water pipes be installed between the utility room and the roof area. A certified NABCEP solar professional should be consulted when installing the actual pipe run as opposed to a pipe chase.
The termination of the pipe chase or pipes should extend above the attic insulation by 6 inches and be located in an area that provides sufficient accessibility and clearance: 18 inches from the top of the chase to the underside of the roof deck. This is so a solar installer can have room to continue the pipe run above the roof deck to the solar array, at a future point in time. If the actual pipes are run to the roof, they must terminate at a universally convenient location relative to the proposed solar array location. The end of the pipe chase or pipes should be labeled to indicate its purpose and intended use.
How to Install a Pipe Chase for Solar Hot Water
- Designate a proposed location and square footage for the solar hot water array on the roof (preferable directly above the utility room).
- Install a single 4” chase or two 2” chases from utility room to the attic space below designated array location.
- Ensure the chase terminates at least 6” above the attic floor insulation (if applicable) and at least 18” below the attic roof deck. Cap both ends.
- Wrap a 3” x 1” label around the chase so the text is visible and upright (if possible). The label should read, “Renewable Energy Ready Home – Solar Thermal Pipe Chase.”
- Record the pipe chase location on a plumbing riser diagram.
Ensure adequate utility room early in the house design process to allow for ample space for solar water heating and photovoltaic system components.
Confirm with local code officials early in the design process what steps are needed to ensure that installation of solar water heating panels will meet with local codes, homeowner's association covenants, and historic district regulations. See the article on building codes and regulations related to solar water heating systems at Energy.gov for additional information.
Protect the electrical and mechanical components of the solar water heating system from bulk moisture, high temperatures, and direct sunlight. The utility room should be properly ventilated and maintain average indoor temperatures.
The DOE Zero Energy Ready Home PV-Ready Checklist (Revision 07) is required only under the following condition related to climate (See the Compliance Tab for other exceptions):
- Location, based on zip code, has at least 5 kWh/m2/day average daily solar radiation based on annual solar insolation using the PVWatts online tool. See map below.
In climates where freezing temperatures are likely to occur, a closed-loop anti-freeze system with heat exchanger will keep outdoor water pipes from bursting.
The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.
Older revisions of the ENERGY STAR Single-Family New Homes National Program Requirements (Rev. 08) stated that “Dwelling units in multifamily buildings with 4 or 5 stories above-grade are eligible to earn the ENERGY STAR if each unit has its own heating, cooling, and hot water systems4, separate from other units, unless the domestic hot water is provided by a solar system. Then (Footnote 4), “Central systems for domestic hot water are allowed for domestic hot water if solar energy provides at least 50% of the domestic hot water needs for the residential units.”
In ENERGY STAR Single-Family New Homes National Program Requirements (Rev. 11), the previous criteria related to heating, cooling, and hot water systems has been removed. The Eligibility Requirements section has been revised to specify that only Dwellings (e.g., single-family homes, duplexes) and Townhouses will be eligible to earn the ENERGY STAR through the Single-Family New Homes program after July 1, 2021. All multifamily dwelling units other than two-family dwellings and townhouses will be required to earn the ENERGY STAR through the Multifamily New Construction (MFNC) program for buildings permitted on or after this date.
National Program Requirements, Version 3 (Rev. 11)
The following site-built or modular1 homes are eligible to earn the ENERGY STAR:
- Dwellings2 (e.g., single-family homes, duplexes)
Dwelling Units in certain low-rise multifamily buildings are also eligible to earn the ENERGY STAR through this program if permitted prior to July 1, 2021. See Footnote 4 for details.4
Please see the ENERGY STAR Single-Family New Homes Implementation Timeline for the program version and revision currently applicable in your state.
1. A modular home is a prefabricated home that is made of multiple modules or sections that are manufactured and substantially assembled in a manufacturing plant. These pre–built sections are transported to the building site and constructed by a builder to meet all applicable building codes for site–built homes.
2. A Dwelling, as defined by ANSI / RESNET / ICC 301, is any building that contains one or two Dwelling Units used, intended, or designed to be built, used, rented, leased, let or hired out to be occupied, or that are occupied for living purposes. ANSI / RESNET / ICC 301 defines a Dwelling Unit as a single unit providing complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking, and sanitation.
3. A Townhouse, as defined by ANSI / RESNET / ICC 301, is a single-family Dwelling Unit constructed in a group of three or more attached units in which each unit extends from the foundation to roof and with open space on at least two sides. Townhouses are also eligible to participate in the ENERGY STAR Multifamily New Construction Program.
4. If permitted prior to July 1, 2021, the following are also eligible to participate in the ENERGY STAR SFNH program:
• Dwelling units 2 in any multifamily building with 4 units or fewer; OR
• Dwelling units in multifamily buildings with 3 stories or fewer above-grade; OR
• Dwelling units in multifamily buildings with 4 or 5 stories above-grade where dwelling units occupy 80% or more of the occupiable square footage of the building. When evaluating mixed–use buildings for eligibility, exclude commercial / retail space when assessing whether the 80% threshold has been met.
Any above-grade story with 20% or more occupiable space, including commercial space, shall be counted towards the total number of stories for the purpose of determining eligibility to participate in the program. The definition of an ‘above-grade story’ is one for which more than half of the gross surface area of the exterior walls is above-grade. All below-grade stories, regardless of type, shall not be included when evaluating eligibility. Per ASHRAE 62.2-2010, occupiable space is any enclosed space inside the pressure boundary and intended for human activities or continual human occupancy, including, but not limited to, areas used for living, sleeping, dining, and cooking, toilets, closets, halls, storage and utility areas, and laundry areas.
Exhibit 1 Mandatory Requirements.
Exhibit 1, Item 1) Certified under the ENERGY STAR Qualified Homes Program or the ENERGY STAR Multifamily New Construction Program.
Exhibit 1, Item 7) Provisions of the Consolidated Renewable Energy Ready Home (RERH) Checklist are completed.
The RERH Checklist requires builders to
- Install a single 4” chase or two 2” chases from utility room to the attic space below designated array location (cap and label both ends). (RERHSWH Guide 3.5)
DOE recommends but does not require solar thermal water systems. See the DOE Zero Energy Ready Home Solar Hot Water-Ready Checklist (Encouraged).
Section 401.3 A permanent certificate shall be posted on or near the electrical distribution panel that lists types and efficiencies of water heating, heating, and cooling equipment, as well as insulation R values, and window U and SHGC factors.
Section R101.4.3 (in 2009 and 2012). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)
Chapter 5 (in 2015, 2018, 2021). The provisions of this chapter shall control the alteration, repair, addition, and change of occupancy of existing buildings and structures.
M2301 Solar Energy Systems (Solar Thermal Energy Systems in 2015, 2018, and 2021 IRC) - See requirements for solar water heating systems.
Appendix U (Appendix T in 2018 IRC and Appendix AT in 2021 IRC) Solar Ready Provisions - Prepare the home for solar installations in accordance with these specifications.
Section R102.7.1 Additions, alterations, or repairs. Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with the requirements of this code, unless otherwise stated. (See code for additional requirements and exceptions.)
Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.
Follow the requirements for solar water heating systems found in the IMC, Chapter 14, Solar Systems (Solar Thermal Systems in 2018 and 2021 IMC).
Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.
The following authors and organizations contributed to the content in this Guide.
Solar hot water systems use energy from the sun to heat water for use in the home. The easiest time to prepare a home for the installation of these systems is during design and construction. A solar hot water-ready home does this by providing plumbing lines from the attic to the hot water heater, chases for wiring, documentation that the roof is designed to support the extra weight of the solar thermal panels, adequate roof space for the solar collector array that is not shaded, and adequate space in the utility room for an additional solar hot water tank, pumps, and controls.