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Dr. Filbert Musau [email protected]
Building Performance Evaluation
Building Fabric Testing
Findings from nine developments across Scotland
Projects
Fabric Testing Methods
Findings
Impacts
Conclusions
Overview
MEARU monitored 7 domestic & 2
non-domestic projects in Scotland
Glasgow
Morrison
Bowmore
Distillery
Lochgelly
Business
Centre
Nine Funded BPE Projects
Projects: history & fabric design aims
Glasgow Lochgelly
Domestic projects
Non-domestic projects
Glasgow
Dunoon Livingston
3 Mainstream flats
3 Sheltered flats
5 are Passivhaus Standard
BPE processes - Fabric tests
As-built construction audit
Thermography
Air-tightness (start and end)
Co-heating test (Whole House Fabric Heat Loss Testing)
In-situ U-value measurements – thermal transmittance
Smoke tests
Not tested - thermal mass
Aims
• To provide an indication of construction quality
• To identify whether specified design targets were met
• To identify opportunities for improvement
Relevance/importance
BPE processes
Thermography
BPE processes - Thermography
Applications in building and construction as a
diagnostic tool
• cold/warm bridging
• insulation continuity
• heat loss – fabric air leaks, missing insulation
• roof moisture ingress & traps – wet insulation
• Tracing heating elements and services - e.g. radiant
heat tubing in floors, ceilings and leaks in those systems
• Location of construction components
BPE processes - Thermography
What are the limitations and sources of error
• Images give only surface temperatures
• Reflected heat from adjacent windows, shiny materials
• Strong winds artificially heat or cool surfaces
• Emissivity: radiated heat of building components
• Angle of reflectance: angles off 90 degrees
• Rain/Surface moisture reflections & cooling of surfaces to even levels
• High levels of dirt or mould change reflectance
• Low-end cameras, less accurate as distance increases
• Focus: improper settings can miss out small details
Results: Thermographic surveys
Results: Thermographic surveys
BPE processes
Air Permeability testing
BPE processes: Air Permeability testing
• Pre Test Requirements
• Liaison with client over time/disruption
• Check weather forecasts (wind speed, temp)
• Building Envelope Calculations
• Air Permeability Area (m2)
• Air Change Rate Volume (m3)
• Building Preparation
• Fully open and restrain internal doors
• Close: lift & internal doors, windows, smoke vents
• Fill with water all drainage traps.
• Seal: incoming service penetrations, trickle ventilators,
passive ventilators and permanently open uncontrolled
NV openings, MV & AC systems
• Turn off: Mech ventilation and AC systems
BPE processes: Air Permeability testing
• Measure
• indoor/outdoor pressure difference
• indoor & outdoor temp before and after test
• barometric pressure before and after test
• Complete test procedure
• pressurisation
• de-pressurisation
• Results
• expressed as a rate of leakage per hour per
square metre of building envelope at a
reference pressure differential of 50 Pa
(m3.h-1.m-2 @ 50 Pa).
Findings: Air Permeability
• Scottish Regulations: below 5m3/m2/hr@50Pa - ‘planned ventilation’ strategy required
• 9/25 have ‘overshot’ the regulation!
• Consensus among scientists - Build Tight, Ventilate Right - how is the IAQ in these?
Findings: Air Permeability
• Challenges testing large buildings
• Differences in results
• between testers
• between pressurisation vs de-pressurisation tests
Findings: Air permeability
0
2
4
6
8
10
12
GA1 GA2 GA3 GB1 GB2 GB3
Mean
Pre
ssu
re a
t 50P
a
(m3
/h/m
2)
Dwelling First Test Second Test
Comparison of first and second air permeability results
• Differences in results after passage of time
• Diversity of performance within the same development and similar construction
Findings: Leakage routes
Leakage points GA1 GA2 GA3 GB1 GB2 GB3
Settlement cracks around windows/window sills √ √ √ √ √ √
Radiators pipes √
Beneath washing machine and kitchen units √ √ √ √
Around waste pipes/ pipe chase for toilet waste pipe √ √ √
Around bath panel √ √ √ √
Electricity services √ √ √ √ √
Heating pipe penetrations √ √ √
Under kitchen units √ √
Light fitting √
Floor to skirting junction/ window to floor junction √ √ √ √
Ventilation system cupboard in hall √ √ √
Around base of built in wardrobe √
Faulty trickle vent √
Air leakage points across the different flats for both 1st test and 2nd tests
BPE processes
U-Value measurements
Element Construction Measured values (W/m2K)
1st floor wall Walls type 2 = Close wall block 0.14 (20% error).
4th floor wall Wall type 1 = timber kit 0.24 (both 5% & 20% error)
Flat Roof Flat Roof 0.36 (both 5% & 20% error)
Comparison of the construction and design & measured U-values in W/(m²K) of various elements
Hukseflux TRSYS01 U-value measurement system
Eltek U-value measurement system
BPE processes: U-Value measurements
BPE processes - U-Value measurements
What are the limitations and sources of error?
• Placing heat flux plates on non uniform elements
• Sol-air temperature – place heat flux plates & temp sensors away from direct solar
• Convection in cavities
• Desired outdoor air temperature for 3 consecutive days
HFP B - Approx. 2.5m
AFFL
HFP A - Approx. 1.2m
AFFL
HFPs mounted at 1.2m and
2.5m above finished floor level. Flux plate located at a cold
element of roof construction
HFP
BPE processes: U-Value measurements
Hukseflux and Eltek air temperature
and Heat Flux sensors mounted on
internal wall surfaces
Air temperature sensors mounted
on external wall surfaces facing
away from the surfaces
BPE processes: U-Value tests
Results:
• Overall most elements exceeded regulation requirements – 23 out of the 31
elements tested achieved building regulations requirement
• Masonry walls produced sometimes unexpected results which could be linked
with possible thermal dynamic effects of the blocks/cavities
Element U-value (W/m2K) - 2007 U-value (W/m2K) - 2010
Wall 0.30 0.27 area weighted av,
Floor 0.25
Roof 0.20
Windows, doors, roof lights 2.20 1.8
Maximum U-values for building elements: Scottish Building Standards, Domestic 2007 and 2010
Results: U-Value tests
Element Design U-value (W/m2K) Actual U-value (W/m2K)
Roof 0.19
Floors 0.15/0.17
Glazing 1.2
Kalwall 0.3 (manufacturer) 0.56 (tested)
Thermalex 0.276 (manufacturer) 0.23 (tested)
Tiled wall 0.2 (Calculated) 0.36 (tested)
Rendered wall 0.2 (Calculated) 0.30 (tested)
Non -domestic Development
Element
Construction
Design values
(W/m2K)
Measured values (W/m2K)
1st floor wall Walls type 2 = Close wall block 0.25 0.14 (20% error).
4th floor wall Wall type 1 = timber kit 0.23 0.24 (both 5% & 20% error)
Flat Roof Flat Roof 0.18 0.36 (both 5% & 20% error)
Domestic Development
Results: U-Value tests
Bldg regs.
Max. values
Design values
Measured values
Element TA1
W/(m2K)
TB1
W/(m2K)
TA1
W/(m2K)
TB1
W/(m2K)
Pitched roofs 0.2 0.13 (0.094) 0.15 0.16
External cavity walls 0.3 0.13/0.18 (0.095) 0.13 0.12
Domestic Development
Construction element Design U-value Measured U-value % Variation
BB1 external wall (block) 0.19W/m2k 0.26W/m2k 26.5
BC1 external wall (timber) 0.19W/m2k 0.198W/m2k 4%
BC1 Roof 0.12W/m2K 0.59W/m2K 491%
Domestic Development
Results: U-Value tests
House type Construction
element
Maximum back
stop value
(W/m2k)
Design
U-value
(W/m2k)
Measured
U-value
(W/m2k)
House Type A External (W) Wall 0.30 0.18 0.14
House Type A
External (W) Roof 0.20 0.16 0.11
House Type B External (N) Wall
0.30 0.27 0.23
House Type B External (E) Roof
0.20 0.14 0.16
House Type C External (N) Wall
0.30 0.15 Circa 20% error
0.07
House Type C External (Flat) Roof
0.20 0.16 Not Passed
0.07
House Type D External (N) Wall
Circa 1.2m FFL
0.30 0.15 0.14
House Type D External (N) Wall
Circa 2.5m FFL
0.30 0.15 0.40
Domestic Development
BPE processes
Whole House Fabric Heat Loss Testing
(Co-heating test)
BPE processes: Co-heating test
• thermostatically controlled heaters and fans
located in the kitchen, living room and bedrooms
• heating systems connected to energy meter
• monitor electrical energy, room temps, external
temp, solar radiation and wind speed & direction
• measurements of the heat flux through the party
wall and the room temps in adjacent house
• Calculation of performance against 3 conditions:
external, adjacent unheated property, sunspace
Co-heating Test: Analysis and Results
Plot 1 Plot 3
Energy Consumption 189.41kWh 155.57kWh
Varied analysis approaches for taking account of solar gains and adjacent temperature
zones - with each providing slightly differing results
1. Linear regression analysis of daily average data:
• Siviour analysis (Siviour, 1981; Everett et al, 1985)
• Leeds Metropolitan University (LMU) method (Wingfield, et al 2000)
2. Dynamic technique:
• LORD program (Gutschker, 2004)
Results - Dynamic analysis using LORD
• Whole house heat loss coefficient is 64.3 W/K
• The solar gain factor is 7.4 m2
Results: Co-heating Test
Siviour analysis
Intercept on the Y-‐axis is the
whole house heat loss coefficient
(Ω-‐value) and the slope the solar
gain factor (gA).
1. Electrical heat input (H)
2. Incident solar radiation (Gsol)
3. Indoor-outdoor temp difference (ΔT).
Results: Co-heating Test
Leeds Met University analysis
Energy impact
What are the energy links?
Building Lifetimes
1. Programming
2. Design
3. Construction
Key Energy Factors
1. Environmental Performance
2. User Comfort & Satisfaction
3. Energy Use
4. Utilisation
Energy impact
Conclusions
• Varied performance in same development and similar construction suggests a
need for better quality assurance, particularly for large developments/buildings
• air permeability rates exceeded regulations requirements in 17/26 dwellings imply
minimised heat loss through exfiltration and cold air ingress through infiltration.
• several air permeability results remained close to stable over time suggesting
robust fabrics. Others varied, suggesting testing inconsistencies, weakening fabric
• The general quality of most of the construction appears to be thermally robust in
the context of U-values, with limited weaknesses identified
• Co-heating test: a single metric attractive, but time, cost and disruption required to
achieve it, and varied analysis approaches could be called in to question
Conclusions
• The good U-value and air permeability imply good heat containment
• While the U-values were generally better standard than the then Regulations, the
current Regulations are tighter and fewer would meet current backstop values.
• backstop air permeability targets have also improved. Some dwellings achieved
much better than the current backstop value
• targeting higher than the minimum requirements does not need to cost significantly
more; and is a good approach to future proofing new developments
• ATTMA std should reduce ambiguity results under negative and positive pressures
• Fabric quality has long term energy impacts on performance
• Some remedial measures possible at minimal cost e.g. sealing leakage points
References
1. All Final Reports of the nine projects
2. MEARU Infrared Measurement Protocols
3. ISO:9869:1994 – U-value Testing
4. TECHNICAL STANDARD L1 and L2. Measuring air permeability of building
envelopes, October 2010 by the Air Tightness Testing and Measurement
Association (ATTMA)
5. BS EN 13829:2001 Method B – Test of the Building Envelope
6. Siviour analysis (Siviour, 1981; Everett et al, 1985)
7. Leeds Metropolitan University (LMU) method (Wingfield, et al 2000)
8. LORD program (Gutschker, 2004)
