Monitoring Results & Specification Traceability

Monitoring Period: July 2008 - 2011 (extended to 3 years) Budget: £30,000 (originally 2-year, extended) Coordinator: Hockerton Housing Project (Nick Martin, Rob Cartwright) Year 1 Report: 22 April 2010

📊 Download Year 1 Interim Report (PDF)

Executive Summary

The Ecoterraces project established a systematic monitoring program linking design specifications to post-occupancy performance verification. The Year 1 interim report (April 2010) revealed a significant performance gap - while EcoHomes Excellent certification was achieved, actual energy consumption exceeded SAP predictions, particularly for space heating.

Key Finding: Space heating energy was 107-130% higher than SAP predictions, likely due to Sunwarm system underperformance or user error.

Positive Result: Total energy consumption was still 27-30% better than UK averages for equivalent property types.

1. Year 1 Monitoring Results (July 2008 - July 2009)

Annual Energy Consumption Summary

Annualized Meter Readings

63 Booth Street

91 London Road

2. Performance Gap Analysis

The Critical Finding: Space Heating

Space heating per m²: - 63 Booth St: 140.4 kWh/m²/yr (SAP predicted: 61.2) - 91 London Rd: 131.2 kWh/m²/yr (SAP predicted: 63.5)

Hot Water Performance (Better than Predicted)

Comparison to UK Averages

Conclusion: Properties perform significantly better than UK average stock, but fall short of the 44% reduction target for Code Level 4.

3. Root Cause Analysis

Suspected Primary Cause: Sunwarm System

The monitoring report identified the Sunwarm ventilation/heat recovery system as the likely source of the performance gap:

1. User Error Identified by Nuaire:
   • Occupants were setting systems to heat in summer and cool in winter (reversed operation)
   • Occupant training recommended
2. Lack of System Monitoring:
   • Sunwarm delivered energy not metered
   • Unable to verify actual system performance vs. manufacturer claims
   • Recommended: Install flow rate meters and heat meters
3. SAP Model Limitations:
   • Sunwarm not available as Appendix Q technology in SAP
   • Standard solar hot water system assumed instead
   • Likely overstated predicted contribution

Secondary Issues Identified

4. SAP Parameters Verified

5. Primary Energy & CO₂ Analysis

Actual vs SAP Predicted

Performance vs SAP: ~29% higher primary energy and CO₂ than predicted

Component Breakdown

6. Monitoring Program Updates

Program Extension

Due to delays in Phase 2 property completion, the monitoring program was extended:

Recommendations from Year 1 Report

1. Install Sunwarm monitoring equipment:
   • Flow rate meters
   • Heat meters
   • Essential to isolate system performance
2. Occupant training:
   • Address reversed Sunwarm operation
   • Correct understanding of controls
3. Fix installation issues:
   • Shower plumbing (completed)
   • Cylinder thermostat settings
4. Continue temperature logging:
   • Data being collected but not yet analyzed
   • Will be included in final report

7. Issues & Discoveries

7.1 Sunwarm System Performance Gap

Problem: Space heating 107-130% higher than SAP predictions Suspected Cause: Sunwarm underperformance or user error Evidence: Nuaire identified reversed operation by occupants Action: Occupant training + recommendation for additional metering

7.2 Shower Installation Error (63 Booth St)

Problem: Electric shower plumbed to hot water cylinder, not mains Impact: Water too hot to use shower; resident forced to take baths Resolution: Plumbing corrected Evidence: Only 1kWh shower consumption Mar-Jul 2009

7.3 Air Tightness Better Than Design Assumption

Design assumed: 5.0 m³/(h·m²) Actual achieved: 7.78-8.1 m³/(h·m²) Impact: Slight SAP adjustment, construction quality validated

7.4 Heating Usage Lower Than SAP Assumes

SAP assumes: 9 hrs/day weekdays, 16 hrs/day weekends Actual (91 London Rd): 4 hrs/day during winter (Nov-Apr) Implication: Even with less heating time, consumption exceeded predictions

8. Specification-to-Monitoring Traceability

Thermal Envelope

Energy Systems - Performance vs Specification

9. Feedback Loops: Phase 1 → Phase 2

Ventilation Strategy Variation

Phase 1 Learning: Sunwarm system performance concerns Phase 2 Decision: Test varied ventilation strategies across properties Benefit: Nuaire offered free product/installation for comparison testing

M&E Standardization

Decision: Apply consistent M&E principles from 63 Booth St to other properties Purpose: Enable direct comparison in monitoring data

Program Extension

Learning: Two properties insufficient for conclusive analysis Decision: Extend to 3 years, await Phase 2 occupancy

10. Key Actors in Monitoring

11. Conclusions

Year 1 Key Findings

1. Performance Gap Identified:
   • Space heating 107-130% higher than SAP predictions
   • Hot water 7-17% better than predictions
   • Overall ~29% worse than SAP for primary energy
2. Root Cause Suspected:
   • Sunwarm system underperformance or user error
   • Lack of system-level metering prevents definitive diagnosis
   • Installation issues (shower plumbing) contributed
3. Positive Outcomes:
   • 27-30% better than UK average housing stock
   • Air tightness exceeded design assumptions
   • EcoHomes Excellent certification achieved
   • Comprehensive metering infrastructure working
4. Recommendations:
   • Install Sunwarm flow rate and heat meters
   • Provide occupant training on system operation
   • Continue monitoring with extended program

The Performance Gap Question

The Year 1 report raises a critical question: Is the gap due to: - Thermal insulation underperformance? - Central heating system underperformance? - Sunwarm system underperformance? - Combination of all three?

The report concludes Sunwarm is the most likely cause, but additional monitoring data is required for definitive proof.

Project Legacy

Despite the performance gap, Ecoterraces demonstrates: - Value of comprehensive post-occupancy monitoring - Importance of system-level metering for diagnosis - Real-world performance can diverge significantly from theoretical models - Occupant behavior and training are critical factors

12. Phase 3: Woodlands House - No Monitoring

Important Note: Phase 3 (Woodlands House, 46 London Road) did not have a post-occupancy monitoring program established.

Implications

Comparison with Phase 1

Lessons

The lack of monitoring for Phase 3 means:

1. No verification of whether improved specifications (higher SAP ratings, PV systems) delivered predicted performance
2. No comparison possible between passive solar (Phase 1 Sunwarm) vs. PV/MVHR (Phase 3) approaches
3. No data to inform future refurbishment projects
4. The Phase 1 monitoring investment becomes even more valuable as the only source of real-world data

Source Documents

• Year 1 Interim Report: Year 1 interim report V1-2 FINAL.pdf (22 April 2010)
• Monitoring Messages: Messages\Monitoring\
• Energy Performance: Messages\Energy performance\
• Air Tests: Messages\Contacts\Air Test Results\
• M&E Specs: Messages\Production Information\M&E spec\