(408) 432-9900

An Architect’s Checklist for Considering Solar Hot Water for Multi-Unit Dwellings

Solar Apt Building Checklist

Solar thermal systems have recently been shown to be cost-competitive with natural gas for multi-unit housing. As a result, architects and developers are increasingly contacting Free Hot Water to find out if solar water heating systems can be integrated with their designs for new apartment buildings, hotels, hospitals, nursing homes, or student dormitory projects.

To give an accurate answer, solar thermal engineers need specific data in order to determine the solar potential, cost, and ROI. To facilitate the proposal process, Free Hot Water has created a comprehensive checklist of information needed to create an accurate solar water heating design and cost estimate for multi-unit dwellings.

The information needed includes:


check_box_opt  The building’s address

Free Hot Water engineers will need this to remotely check your annual insolation—the yearly amount of sunlight that will potentially hit the roof of your project. It’s also important for permitting and other factors.

check_box_opt  Do you have a southern oriented roof?
In North America, the sun crosses the horizon in southern orientation, which is optimal for solar thermal production. Your roof can face east or west, as well, but southern exposure is best. For flat roofs, this can also be a concern when taller surrounding buildings block the sun.

check_box_opt  The locations of any buildings or trees that may cast shade on panels

If your landscape design will include trees or you’ll have other buildings that may block sunlight, we will need to account for this in our designs.

check_box_opt  The number of floors

Knowing the number of floors is important for designing pump stations that are strong enough to circulate the solar thermal fluid throughout the building.

check_box_opt  The building’s footprint with dimensions

We’ll need this to account for the number and type of solar thermal collectors, piping, as well as other considerations.

check_box_opt  Design images of the building from the side view

Free Hot Water engineers endeavor to make pipes and other external solar infrastructure as unobtrusive as possible, so it’s important for us to see the potential areas where pipes or storage tanks can be placed.


Specific roof dimensions will help engineers to design the most optimal solar thermal system within the available area. Therefore, it’s important for us to have the following dimensions:

check_box_opt  Roof height

check_box_opt  Roof dimensions

check_box_opt Roof slopes (for example, 4:12), hips, peaks and valleys

check_box_opt Locations & footprint dimensions of all rooftop equipment to be avoided (HVAC vents, skylights, etc.)

check_box_opt Please identify any rooftop equipment that may cast shade on solar panels

check_box_opt Roof framing information (size and locations of roof framing members, roof deck type, etc.)

check_box_opt If applicable, please indicate the roof section where you would like the solar collectors to be installed. If flexible, we will suggest the best area.


Solar thermal storage tanks can be placed indoors, outdoors, or even underground.

check_box_opt Storage tank location

If storage tanks can be placed outdoors, we will need the dimensions of the area where tanks are to be located, as well as adjacent structures, etc. If indoors, we’ll need to know the location of the mechanical room in the current design.

check_box_opt Plan dimensions of all walls outlining mechanical room

This will determine the potential for the potential volume of solar hot water storage and space needed for other equipment, such as the pump station and backup heating tanks.

check_box_opt  Location and size of all wall openings (doors, windows, louvers, etc.)

Storage tanks come in different shapes and sizes.  We’ll use this information to determine the type and size of storage tanks that can be brought through the doors or other access areas.

Similarly, we’ll also need the ceiling height in order to ensure that the room’s height is adequate for tank clearance.

check_box_opt  Location and size of all other equipment planned for the mechanical room If other equipment needs to be housed in the same mechanical room, we’ll need a list of these items. (boilers, pumps, tanks, machinery, washers, dryers, wall-mounted equipment, etc.)

check_box_opt  Slab information

If storage tanks will be mounted on an existing or pre-designed slab, we will need slab information (depth, reinforcing, etc.) Alternatively, your solar thermal engineer can design the correct size slab.

check_box_opt  City infrastructure

We’ll need the call out pipe diameter of city water inlet and domestic hot water outlet for the building.


check_box_opt  Elevation view(s)

Depending on your city’s permitting requirements, we may need the elevation view(s) of building (with dimensions, or in a scalable format)


check_box_opt  Control options

Do the solar hot water controls need to be tied into the building controls? Or can they operate independently?  Free Hot Water’s engineers can design control and maintenance solutions for both options.

Of course, depending on your architectural and budget goals, your solar thermal engineering team may need additional data or specifications. If you’d like to know more, please contact Free Hot Water for a free solar thermal engineering consultation.

This entry was posted in Architects and Solar Hot Water, pre-engineered solar thermal systems, Solar Business Resources, solar thermal engineering. Bookmark the permalink.

Comments are closed.