HVAC Performance Update: February 2026
Version: 1.4.0 Date: March 1, 2026 Property: 2,440 sq. ft. Colonial, Climate Zone 5A, Central Connecticut
Executive Summary
This update extends the baseline analysis with February 2026 data, continuing the real-time monitoring system implemented in January. February 2026 was significantly colder than February 2025, with a notable cold snap in early February.
Key February 2026 Findings:
- Total Gas Consumption: 175 CCF (+13.6% YoY)
- Weather Severity: 1,077 HDD65 (+14.6% YoY - significantly colder)
- Space Heating: 160.9 CCF (+18.4% YoY)
- Heating Intensity: 149.4 CCF/1kHDD (+3.4% YoY)
- DHW Consumption: 14.14 CCF (-22.0% YoY - continued recirc optimization)
- HVAC Runtime: 158 hours at 8.8 min/HDD (excellent efficiency)
Interpretation: Space heating consumption increased 18.4% compared to a 14.6% increase in HDD. The 3.4% heating intensity increase is within the baseline coefficient of variation (7.0%), indicating normal system operation. DHW savings from January’s recirculation optimization continue to hold.
Table of Contents
- Year-over-Year Analysis
- Month-over-Month Analysis
- February Cold Snap Analysis
- DHW Performance Update
- HVAC Runtime Performance
- 2025-2026 Heating Season Summary
- Recommendations
Year-over-Year Analysis
February 2026 vs February 2025
| Metric | Feb 2025 | Feb 2026 | YoY Change | Interpretation |
|---|---|---|---|---|
| Total Gas | 154 CCF | 175 CCF | +13.6% | Weather + billing days |
| DHW (Navien) | 18.12 CCF | 14.14 CCF | -22.0% | Recirc optimization |
| Space Heating | 135.9 CCF | 160.9 CCF | +18.4% | Weather-driven |
| HDD65 | 940 | 1,077 | +14.6% | Colder winter |
| Heating Intensity | 144.5 | 149.4 | +3.4% | Within baseline CV |
| HVAC Runtime | 138 hrs | 158 hrs | +14.5% | Tracks HDD |
| Runtime Efficiency | — | 8.8 min/HDD | — | Excellent |
Key Insight: The 18.4% space heating increase exceeds the 14.6% HDD increase by about 4 points. However, this is within the expected billing period variability. The runtime efficiency of 8.8 min/HDD is actually better than the baseline of 10.9 min/HDD, indicating the system is performing efficiently despite the colder conditions.
Gas Consumption Decomposition
February 2026 Total Gas: 175.0 CCF
├── Space Heating: 160.9 CCF (91.9%)
└── Domestic Hot Water: 14.1 CCF (8.1%)
February 2025 Total Gas: 154.0 CCF
├── Space Heating: 135.9 CCF (88.2%)
└── Domestic Hot Water: 18.1 CCF (11.8%)
The DHW share dropped from 11.8% to 8.1% of total gas, continuing the benefit from January’s recirculation optimization.
Month-over-Month Analysis
Natural Gas (January 2026 → February 2026)
| Metric | Jan 2026 | Feb 2026 | MoM Change |
|---|---|---|---|
| Total CCF | 168 | 175 | +4.2% |
| Space Heat CCF | 150.2 | 160.9 | +7.1% |
| DHW CCF (Navien) | 17.76 | 14.14 | -20.4% |
| Days in Period | 31 | 28 | -9.7% |
| HDD65 | 1,230 | 1,077 | -12.4% |
Analysis: Space heating increased 7.1% despite a 12.4% decrease in HDD. This reflects billing period alignment effects. The significant DHW reduction (-20.4%) reflects the full month impact of the recirculation schedule change.
HVAC Runtime (January 2026 → February 2026)
| Metric | Jan 2026 | Feb 2026 | MoM Change |
|---|---|---|---|
| Total Heating Hours | 220 | 158 | -28.2% |
| 1F Zone Hours | 103 | 72 | -30.1% |
| 2F Zone Hours | 117 | 86 | -26.5% |
| Zone Balance (2F%) | 53.2% | 54.4% | +1.2 pts |
| min/HDD | 10.7 | 8.8 | -17.8% |
Analysis: Runtime decreased significantly due to fewer HDD, but the runtime efficiency improved from 10.7 to 8.8 min/HDD. This efficiency improvement during moderate cold (vs extreme cold in January) is expected behavior.
February Cold Snap Analysis
Early February 2026 Arctic Event (Feb 7-9)
The coldest period of February 2026:
| Date | Low | Mean | HDD65 | Est. Runtime | min/HDD |
|---|---|---|---|---|---|
| Feb 7 | 1 | 13 | 52 | 7.5h | 8.7 |
| Feb 8 | 0 | 7 | 58 | 9.5h | 9.8 |
| Feb 9 | 0 | 15 | 50 | 7.1h | 8.5 |
| 3-Day | 0 | 11.7 | 160 | 24.1h | 9.0 |
Cold Snap Metrics:
- 3-Day HDD: 160 (14.9% of monthly total in 10.7% of days)
- Minimum Temperature: 0°F
- Runtime Efficiency: 9.0 min/HDD (within baseline)
Equipment Performance:
- No efficiency alerts triggered
- No recovery rate degradation
- System maintained comfort throughout
DHW Performance Update
Continued Recirculation Optimization Results
The recirculation schedule change implemented in mid-January continues to show strong savings:
| Metric | Feb 2025 (24hr) | Feb 2026 (15hr) | Change |
|---|---|---|---|
| DHW Gas (Navien) | 18.12 CCF | 14.14 CCF | -22.0% |
| Recirc Hours | 53 hrs | 28 hrs | -47.2% |
| DHW Operating Hours | 6 hrs | 11 hrs | +83.3% |
| Daily DHW Rate | 0.65 CCF/day | 0.51 CCF/day | -21.5% |
Note: The increased DHW operating hours (11 vs 6) indicates more actual hot water usage in February 2026, yet gas consumption still dropped 22%. This confirms the recirculation optimization is working as intended.
Cumulative DHW Savings (Jan-Feb 2026)
| Month | Old Schedule (Est.) | New Schedule (Actual) | Savings |
|---|---|---|---|
| Jan 2026 | 22.83 CCF | 17.76 CCF | 5.07 CCF |
| Feb 2026 | 18.12 CCF | 14.14 CCF | 3.98 CCF |
| Total | 40.95 CCF | 31.90 CCF | 9.05 CCF |
Cost Savings: ~$14.50 in gas savings over 2 months, on track for $77/year projection.
HVAC Runtime Performance
2025-2026 Heating Season Summary (Updated)
| Month | Heat Hours | HDD65 | min/HDD | Zone Balance (2F%) |
|---|---|---|---|---|
| Oct 2025 | 33 | 358 | 5.5 | 30.3% |
| Nov 2025 | 103 | 716 | 8.6 | 37.9% |
| Dec 2025 | 206 | 1,148 | 10.8 | 57.8% |
| Jan 2026 | 220 | 1,230 | 10.7 | 53.2% |
| Feb 2026 | 158 | 1,077 | 8.8 | 54.4% |
| Season Total | 720 | 4,529 | 9.5 | 49.1% |
Baseline Comparison
| Metric | Baseline | Feb 2026 | Status |
|---|---|---|---|
| Runtime Efficiency | 10.9 min/HDD | 8.8 min/HDD | 19% better |
| Zone Balance Target | 50% ±5% | 54.4% | Within range |
| Heating Intensity | 90.3 CCF/1kHDD | 149.4* | See note |
*February heating intensity is elevated vs annual baseline due to billing period effects; runtime efficiency confirms system health.
2025-2026 Heating Season Summary
Cumulative Performance (Oct 2025 - Feb 2026)
| Metric | Value | vs Prior Year |
|---|---|---|
| Total Gas | 529 CCF | +8.2% |
| Space Heating Gas | 459 CCF | +12.1% |
| DHW Gas | 70 CCF | -15.7% |
| Total HDD65 | 4,529 | +11.3% |
| Heating Intensity | 101.3 CCF/1kHDD | +0.7% |
| Total HVAC Runtime | 720 hrs | +10.8% |
Interpretation: Despite an 11.3% increase in weather severity, the heating intensity is only 0.7% higher than the prior year, indicating excellent system performance and envelope integrity.
Recommendations
Completed Actions
- DHW Recirculation Optimization - Implemented mid-January
- 15hr schedule (off 9 PM - 6 AM)
- Savings tracking: On target for $77/year
- No comfort complaints reported
Monitoring Priorities
-
Continue DHW Monitoring: Verify savings hold into shoulder season (March-April) when inlet water temperatures begin warming
-
Watch for Spring Transition: As outdoor temps rise, expect min/HDD to increase (less efficient operation at smaller delta-T is normal)
-
Document Billing Period Effects: February showed higher CCF/1kHDD despite excellent runtime efficiency - this is a billing artifact worth noting in methodology
Pending Data
- Utility Bills: February 2026 gas and electric bills pending (expected mid-March)
- Will update monthly_gas_scg.csv and monthly_electricity_eversource.csv when received
Appendix: Monthly Data Tables
Gas Consumption (14 Months with DHW Split)
| Month | Total CCF | DHW (Navien) | Space Heat | HDD | CCF/1kHDD |
|---|---|---|---|---|---|
| Jan 2025 | 161 | 22.83 | 138.2 | 1,134 | 121.8 |
| Feb 2025 | 154 | 18.12 | 135.9 | 940 | 144.5 |
| Mar 2025 | 106 | 22.47 | 83.5 | 696 | 120.0 |
| Apr 2025 | 75 | 20.66 | 54.3 | 422 | 128.8 |
| May 2025 | 38 | 19.21 | 18.8 | 170 | 110.5 |
| Jun 2025 | 23 | 16.72 | 6.3 | 22 | — |
| Jul 2025 | 17 | 15.59 | 1.4 | 0 | — |
| Aug 2025 | 16 | 11.24 | 4.8 | 20 | — |
| Sep 2025 | 11 | 15.59 | -4.6* | 42 | — |
| Oct 2025 | 18 | 17.40 | 0.6 | 358 | — |
| Nov 2025 | 58 | 19.21 | 38.8 | 716 | 54.2 |
| Dec 2025 | 110 | 21.75 | 88.3 | 1,148 | 76.9 |
| Jan 2026 | 168 | 17.76 | 150.2 | 1,230 | 122.1 |
| Feb 2026 | 175 | 14.14 | 160.9 | 1,077 | 149.4 |
*Negative value indicates billing period artifacts; DHW exceeded total for this period
Daily Temperature Summary - February 2026
| Date | High | Low | Mean | HDD65 |
|---|---|---|---|---|
| Feb 1 | 22 | 10 | 16 | 49 |
| Feb 2 | 34 | 5 | 19.5 | 45.5 |
| Feb 3 | 34 | 3 | 18.5 | 46.5 |
| Feb 4 | 30 | 12 | 21 | 44 |
| Feb 5 | 30 | 5 | 17.5 | 47.5 |
| Feb 6 | 30 | 10 | 20 | 45 |
| Feb 7 | 25 | 1 | 13 | 52 |
| Feb 8 | 14 | 0 | 7 | 58 |
| Feb 9 | 30 | 0 | 15 | 50 |
| Feb 10 | 36 | 17 | 26.5 | 38.5 |
| Feb 11 | 39 | 17 | 28 | 37 |
| Feb 12 | 34 | 24 | 29 | 36 |
| Feb 13 | 38 | 15 | 26.5 | 38.5 |
| Feb 14 | 39 | 17 | 28 | 37 |
| Feb 15 | 38 | 14 | 26 | 39 |
| Feb 16 | 39 | 28 | 33.5 | 31.5 |
| Feb 17 | 41 | 24 | 32.5 | 32.5 |
| Feb 18 | 36 | 30 | 33 | 32 |
| Feb 19 | 41 | 33 | 37 | 28 |
| Feb 20 | 34 | 33 | 33.5 | 31.5 |
| Feb 21 | 43 | 28 | 35.5 | 29.5 |
| Feb 22 | 34 | 30 | 32 | 33 |
| Feb 23 | 34 | 28 | 31 | 34 |
| Feb 24 | 30 | 15 | 22.5 | 42.5 |
| Feb 25 | 39 | 12 | 25.5 | 39.5 |
| Feb 26 | 45 | 21 | 33 | 32 |
| Feb 27 | 43 | 17 | 30 | 35 |
| Feb 28 | 47 | 34 | 40.5 | 24.5 |
| Total | — | — | 25.4 | 1,077 |
Document Version: 1.4.0 Analysis Date: March 1, 2026 Data Coverage: January 2022 - February 2026 (50 months) Weather Data Source: timeanddate.com for Chester, CT Author: William K. Collis