A community group has $100,000 in pledges and hopes to land at least $100,000 more over the next few weeks to secure the installation of energy efficient HVAC equipment at Central Grade School. Though work has already begun, exactly what type of HVAC system will heat and cool the new building remains to be seen. The board agreed earlier this month to let a community group led by local architect Suzannah Tobin raise money for the added cost. The amount dropped to $443,069 after a pledged $125,000 rebate for the hybrid system from Traverse City Light & Power. HVAC parts have to be ordered by Oct. 12, with a decision on whether to pursue the hybrid system likely made well before that.