Name: DWTI System — ASHRAE Setty Family Foundation Challenge 2026
Uploaded: 2026-05-03
Duration: 14 min 20 s
Description: ASHRAE COMPETITION 2026. DOMESTIC WATER. THERMAL INTEGRATION.

ASHRAE COMPETITION 2026. DOMESTIC WATER. THERMAL INTEGRATION. 

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DWTI — Ground Source Heat Pump Integration for Residential Space Conditioning

Climate Zone 4A  •  2,400 ft² Reference Dwelling  •  May 4, 2026

THE ENERGY CHALLENGE. 45–50%. of residential energy goes to HVAC. 

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of all household energy = thermal management

Residential Energy Space Conditioning Water Heating Other 47 16 37

⚡  Ground Loop Thermal Imbalance degrades GSHP efficiency 10–18% over 20 years — DWTI directly solves this.

HOW THE DWTI SYSTEM WORKS. ☀️ COOLING MODE. Summer Operation. 

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SYSTEM ARCHITECTURE & KEY COMPONENTS. GSHP UNIT 5-ton Capacity. 

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Preheats domestic hot water supply (Cooling season)

Extracts heat from cold water supply (Heating season)

🖥  BMS Controller  |  8 Sensors  |  Modbus/BACnet

DOMESTIC WATER PROFILES & THERMAL POTENTIAL. DHW Rejection (Btu/day) Summer Spring/Fall Winter 18200 16400 14700 DCW Extraction (Btu/day) Summer Spring/Fall Winter 3100 7900 12800. 

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DOMESTIC WATER PROFILES & THERMAL POTENTIAL

DHW Rejection (Btu/day) Summer Spring/Fall Winter 18200 16400 14700 DCW Extraction (Btu/day) Summer Spring/Fall Winter 3100 7900 12800

Parameter Summer Winter DHW Demand 55.4 gal/day 62.8 gal/day Cold Water Supply 197.3 gal/day 188.6 gal/day CW Supply Temp 68–74°F 42–50°F DHW Savings ~38% ~24% DCW Extraction Low High Combined Offset 21,300 Btu/day 27,500 Btu/day

SAFETY LIMITS:  DCW outlet ≥ 39°F (4°C)   |   DHW storage ≥ 140°F (60°C) — Legionella compliance per ASHRAE Guideline 12

VALVING, CONTROLS & FAIL-SAFE LOGIC. COOLING MODE. 

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V101: DHW HX Active V103: Bypass V105: Closed

V101: Bypass V103: DCW HX Active V105: Open

All valves default to ground loop (space conditioning preserved)

Valve Description Cooling Heating Fail-Safe V101 Condenser → DHW HX DHW Active Bypass Bypass V103 DCW Supply → HX-2 Bypass DCW Active Direct Supply V105 GL Bypass around HX-1 Closed Open Open V106 Emergency isolation Open Open Manual

8 sensors  •  30-second scan rate  •  5-second safety override  •  Modbus/BACnet integration

LIFE CYCLE ANALYSIS — ENVIRONMENTAL IMPACT. 225–240. 

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LIFE CYCLE ANALYSIS — ENVIRONMENTAL IMPACT

kWh Saved/Year Space Heating DHW Preheat Space Cooling Cold Water Pre-cool Pumps/Controls 23370 13468 9516 4736 330

GWP reduced 38–43%  |  CED reduced 32–37%  |  Embodied carbon payback: 18–24 months  |  72–78% end-of-life material recovery

FINANCIAL FEASIBILITY ANALYSIS. $57,959. Total Installed Cost (2025 USD). 

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Cost Ground Loop GSHP Unit Labor Mech. Controls/BMS DHW+DCW HX Other 18500 8200 11400 2600 2350 9200

Federal ITC 30% → ~$17,388 credit  |  NY Clean Heat: $1,500–$3,500/ton  |  MA MassSave: up to $15,000  |  NC REITC: 15%

ASHRAE COMPLIANCE & ABOVE-CODE PERFORMANCE. ASHRAE 90.1-2022. 

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ASHRAE COMPLIANCE & ABOVE-CODE PERFORMANCE

COP ≥3.6 (min 3.1) EER ≥17.1 (min 14.0)

Hydronic reset 85–120°F No radiant asymmetry

DHW ≥140°F Legionella control maintained

Metric Code Min Design Value Improvement Heat Pump COP (Heating) 3.1 ≥ 3.6 +16% Heat Pump EER (Cooling) 14.0 ≥ 17.1 +22% DHW Energy Factor 0.82 EF 3.2–3.8 eff. EF +290–363% Refrigerant GWP R-410A: 2,088 R-454B: 466 −78%

RETROFIT COMPATIBILITY & SCALABILITY. 🔧. Retrofit-First Design. 

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Compatible with existing GSHP systems — no new bore drilling required. Skid-mounted module fits standard mechanical room.

Hotels: 40–55% DHW savings. Multi-family: load diversity benefit. Office: supplemental ground-loop source.

Solar thermal adds 55–65% GWP reduction. DWHR on drain stack saves 2,800–4,200 kWh/yr additionally.

CZ 2–3: DHW rejection dominates. CZ 5–7: DCW extraction dominates. Near-balanced CZ 4A: full dual benefit.

KEY PERFORMANCE SUMMARY. 4.2–4.8. Heating COP. 19.5–22.3. 

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CONCLUSIONS & RECOMMENDATIONS. CONCLUSIONS. ✓. Technical feasibility firmly established — all components commercially available. 

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Technical feasibility firmly established — all components commercially available

Complies with all ASHRAE standards; exceeds code minimums by 16–363%

38–43% GWP reduction and 32–37% CED reduction vs. conventional GSHP

Positive NPV at any discount rate up to 8.5% — robust economics

Cross-contamination prevention through double-wall HX with pressure differential

Pilot in Climate Zones 2A & 6A — 2 full heating/cooling seasons

Calibrated ground thermal models from actual boring logs

IAPMO/ICC code pathway development for domestic water integration

Factory-integrated desuperheater/DCW HX assembly (single SKU)

Occupant behavior research for control algorithm optimization

DWTI System — 2026 ASHRAE Setty Family Foundation Applied Engineering Challenge  |  Climate Zone 4A  |  2,400 ft² Reference Dwelling

DWTI System — ASHRAE Setty Family Foundation Challenge 2026

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