R362-2-8. Investment Tax Credit, Eligible Costs for Commercial and Residential Systems, Passive Solar

  (A) An eligible passive solar system must be purposefully designed to use the structure of a building to collect, store, and distribute heating or cooling to a building and to do so at the appropriate season and time of day. (For example providing heat in winter or at night but not during summer days.) All passive solar systems should contain the following in order to be eligible:

  1. A means to allow the solar energy to enter the system;

  2. A heat-absorbing surface;

  3. A thermal storage mass located within the conditioned space;

  4. A heat transferal system or mechanism and;

  5. Protection from summer overheating and excessive winter heat-loss.

  A passive system must receive an average of at least four hours of sunlight per day during the winter months of December through March and shall be primarily south facing.

  (B) Eligible costs for a passive solar system include the costs of the following:

  1. Trombe wall;

  2. Water wall;

  3. Thermosyphon;

  4. Equipment or building shell components providing direct heat gain; and

  5. Any item that can be demonstrated to be a component of a purpose-built system to collect, store and transport heat from the sun. The cost of ventilation, fans, movable insulation, louvers, overhangs and other shading devices shall be eligible provided that they are designed to be used as an integral part of the passive solar system and not part of the conventional building design.

  (C) The cost of a solarium is also considered to be eligible if it provides heat to the living space of the house in conjunction with a thermal storage mass and a forced or natural convection heat transportation design. Solariums must also be designed to prevent heat loss at night by means of insulation devices. They must also be designed so as to prevent summer heating that would increase the load on the building's cooling system.

  (D) The cost of windows and other glazing devices are eligible only when they are part of a passive solar system that uses thermal mass storage and a passive or active heat transportation system to provide heating throughout the building. In addition, windows and other glazing devices are eligible only when they are oriented within 30 degrees of true south and when they are installed with shading devices or overhangs that prevent direct sun from entering the building in the summer while allowing direct sun in the winter. Windows and other glazing devices must also carry solar heat gain coefficient (SHGC) ratings of 0.50 or higher in order to allow sufficient amounts of heat into the building, but must carry a U-factor rating of 0.35 or less in order to provide sufficient insulation to the building.

  (E) The cost of heat transportation systems shall be eligible provided they are part of the passive solar design and will not be used as part of a conventional heating system.

  (F) Costs for the thermal storage mass of a passive solar system are eligible subject to the following:

  1. For a non-loaded structure, 100% of the cost may be eligible;

  2. For a loaded structure, 50% of the cost may be eligible;

  3. Notwithstanding (1) and (2) above, the cost of thermal storage mass may not exceed 30% of the total system cost against which a tax credit is calculated.

  (G) No tax credit shall be given if OED concludes that the passive solar system does not supply heating when needed or allows more heat loss than gain in the winter months or overheating in the summer months.