I’ve been gradually building up a summary of the main features that I plan to include in the Little Rental House. Some of these will go in with the first build; others might be “nice-to-haves” that get added once the home is actually ready for occupancy.
- Accessible
- ADA-compliant parking space
- ADA-compliant bathroom, kitchen, living areas
- ADA-compliant entrance ramps, etc.
- Efficient resource use for heating and cooling
- Walls, ceiling, and floor all insulated to better than R-40.
- Double (or maybe triple) glazed windows for heat retention.
- Heated with air-source heat pump to minimize power required.
- Heat-recovery ventilator to provide fresh air with minimum heat loss.
- Hot water heating inside heated space (reduces heat loss)
- Drain water heat recovery unit
- Minimum water footprint
- Rainwater collection with filtration and UV sterilization
- Downcycling of greywater for toilet flushing
- Minimum power requirements
- Low-voltage LED lighting used throughout to save power (< 0.25kWh/day)
- DC refrigerator (< 0.7kWh/day)
- Direct outlets for DC appliances (24V, 5V USB)
- Two stage water heating with ultra-insulated storage (30 gal, est. < 0.5kWh/day) plus on demand system for large volume use (AC only)
- Water pumping using low power, low voltage DC pumps (< 0.1kWh/day including sterilization)
- Heat recovery from waste water (bathtub, clothes washer, sinks)
- Grid-flexible solar power generation
- Battery storage (about 10 kWh) for approximately 6 days including hot water, up to 2 days with constant heating.
- Online inverter provides whole-house “uninterruptible” power supply
The City of Ithaca and Town of Ithaca are working on a new joint “energy code supplement” to encourage green building. New construction should get a minimum of 6 “points” in their system. My rough calculation for the proposed home is 11 points:
- EE1: air source heat pump = 3 points
- AI1: smaller building size = 2 points (under 1120 sq ft)
- AI2: heating system in heated space = 1 point
- AI5: modest window-to-wall ratio (13%) = 1 point
- RE1: on-site renewable electric = 3 points (2350 kWh/year / 648 sf > 3.6)
- OP4: meet NYStred Code-2020 Version 1.0 = 2 points (maybe, complex to evaluate)