For co-ops and condos needing to balance energy efficiency with financial constraints, the experience of 668 Riverside Drive, a 64-unit prewar condo in Hamilton Heights, offers insights. The building recently fine-tuned its boiler and steam heat operations to reduce costs by around 10% — without the need for an assessment. The work, including an initial energy audit, cost around $25,000 after NYSERDA and Con Edison incentives covered roughly 50% of the upgrades.    Read the article…………………………….