Due to popular demand, I have put together a summary of my research findings and in particular, implications for industry and practical insulation installation
Disclaimer: The Author does not accept any responsibility for the subsequent use of this information, for any errors or omissions that it may contain, or for any misunderstandings arising from it. NOTE: research conducted mainly in pre-1919 houses in England (i.e. with uninsulated solid brick walls).
Disclaimer: The Author does not accept any responsibility for the subsequent use of this information, for any errors or omissions that it may contain, or for any misunderstandings arising from it. This research was funded by the EPSRC Centre for Doctoral Training in Energy Demand (LoLo), grant numbers EP/L01517X/1 and EP/H009612/1 while the corresponding author was at UCL. The authors are also very grateful for the support of: the Belgian Chair Charity Fund administered by the Embassy of Belgium in London, to the homeowners for access to the case study houses and to Salford City West Housing Association, Carbon Co-op, NBT, Knauf, Energy Savings Trust and Downs Energy for support of the studies at different stages. |
Links and other resources
Latest papersVoid conditions and potential for mould growth in insulated and uninsulated suspended timber ground floors (paid for access)
Suspended timber ground floors: Heat loss reduction potential of insulation interventions (free to access) Press Releases"Research shows underfloor insulation can reduce heat loss in older homes by 92%" (Oct 2017)
"Ground-floor insulation can reduce floor heat loss by up to 92 percent" (Oct 2017) "New research finds potential for greater retrofit energy savings in homes" (June 2017) Current researchMy PhD journeyMy Final PhD thesis can be downloaded here ("Pre-1919 suspended timber ground floors in the UK: estimating in-situ U-values and heat loss reduction potential of interventions")
Some images and description of my field studies, including insulation installation images and link to a short talk and discussion (2013-15) |
Collage of field work undertaken by the author during the 2013-14 winter, which included measuring floor heat-loss on several points across a floor, with the instruments as shown. Image copyright by © Sofie Pelsmakers
Research summaries
Heat-flow variability of suspended timber ground floors: Implications for in-situ heat-flux measuring
S.Pelsmakers, R.Fitton, P.Biddulph, W.Swan, B.Croxford, S.Stamp, F.C.F.Calboli, D.Shipworth, R.Lowe, C.A.Elwell
Energy and Buildings, Volume 138, 1 March 2017, Pages 396-405
https://doi.org/10.1016/j.enbuild.2016.12.051
ABSTRACT
Reducing space heating energy demand supports the UK’s legislated carbon emission reduction targets and requires the effective characterisation of the UK’s existing housing stock to facilitate retrofitting decision-making. Approximately 6.6 million UK dwellings pre-date 1919 and are predominantly of suspended timber ground floor construction, the thermal performance of which has not been extensively investigated. This paper examines suspended timber ground floor heat-flow by presenting high resolution in-situ heat-flux measurements undertaken in a case study house at 15 point locations on the floor. The results highlight significant variability in observed heat-flow: point U-values range from 0.56 ± 0.05 to 1.18 ± 0.11 Wm−2 K−1. This highlights that observing only a few measurements is unlikely to be representative of the whole floor heat-flow and the extrapolation from such point values to whole floor U-value estimates could lead to its over- or under- estimation. Floor U-value models appear to underestimate the actual measured floor U-value in this case study. This paper highlights the care with which in-situ heat-flux measuring must be undertaken to enable comparison with models, literature and between studies and the findings support the unique, high-resolution in-situ monitoring methodology used in this study for further research in this area.
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Suspended timber ground floors: measured heat loss compared with models
S. Pelsmakers, B. Croxford & C.A. Elwell, Building Research and information, 2017
www.tandfonline.com/doi/full/10.1080/09613218.2017.1331315
ABSTRACT
There are approximately 6.6 million dwellings in the UK built before 1919, predominantly constructed with suspended timber ground floors whose thermal performance has not been extensively investigated. The results are presented from an in-situ heat-flow measuring campaign conducted at 27 locations on a suspended timber ground floor, and the estimated whole-floor U-value compared with modelled results. Findings highlight a significant variability in heat flow, with increased heat loss near the external perimeter. In-situ measured-point U-values ranged from 0.54 ± 0.09 Wm−2 K−1, when away from the external wall perimeter, to nearly four times as high (2.04 ± 0.21 Wm−2 K−1) when near the perimeter. The results highlight the fact that observing only a few measurements is likely to bias any attempts to derive a whole-floor U-value, which was estimated to be 1.04 ± 0.12 Wm−2 K−1and nearly twice that derived from current models. This raises questions about the validity of using such models in housing stock models to inform retrofit decision-making and space-heating-reduction interventions. If this disparity between models and measurements exists in the wider stock, a reappraisal of the performance of suspended timber ground floors and heat-loss-reduction potential through this element will be required to support the UK’s carbon-emission-reduction targets.
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Suspended timber ground floors: Heat loss reduction potential of insulation interventions
S.Pelsmakers, C.A.Elwell
Energy and Buildings, Volume 153, 15 October 2017, Pages 549-563
https://doi.org/10.1016/j.enbuild.2017.07.085
ABSTRACT
There are approximately 10 million suspended timber ground floor constructions in the UK and millions more globally. However, it is unknown how many of these floors are insulated and their performance has not been widely investigated. This study investigates the impact of retrofitting insulation on the thermal performance of suspended timber ground floors through the detailed investigation of a UK case study dwelling. Practical and buildable interventions were undertaken: fully-filling the floor void with EPS beads, and 100 mm woodfibre insulation between the joists. The performance of both interventions was monitored by high-resolution in-situ heat-flow monitoring in 27 floor locations, allowing for comparison with the uninsulated floor and with modelled results. While floors often remain uninsulated due to the disruption of retrospective works, this study highlighted potentially significant heat loss reductions: the mean whole floor U-value dropped by 65% for woodfibre insulation and 92% for bead-insulation which also benefited from sealed airbricks. A disparity between the in-situ measured and modelled performance was observed; this gap reduced the better insulated the floor was. The findings have implications for policy, retrofit decision-making and carbon emission reduction stock models, especially given the modelled underestimation of floor heat loss, impact of interventions and assumed financial payback for this study.
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Void conditions and potential for mould growth in insulated and uninsulated suspended timber ground floors
Pelsmakers, S., Vereecken E., Airaksinen, M., Elwell, C.A.
Special Issue Paper: Enthalpy, Moisture, and Ventilation Issues in Buildings in International Journal of Building Pathology and Adaptation (Guest editors William Isaacs and William Rose, Steve McNeil)
DOI 10.1108/IJBPA-05-2018-0041 (no free access)
ABSTRACT
Purpose: Millions of properties have suspended timber ground floors globally, with around 10 million in the UK alone. However, it is unknown what the floor void conditions are, nor the effect of insulating such floors. Upgrading floors changes the void conditions, which might increase or decrease moisture build-up and mould and fungal growth. This paper provides a review of the current global evidence and presents the results of in-situ monitoring of 15 UK floor voids.
Research method: An extensive literature review on the moisture behaviour in both uninsulated and insulated suspended timber crawl spaces is supplemented with primary data of a monitoring campaign during different periods between 2012 to 2015. Air temperature and relative humidity sensors were placed in different floor void locations. Where possible, crawl spaces were visually inspected.
Implications: Comparison of void conditions to mould growth thresholds highlights that a large number of the monitored floor voids might exceed the critical ranges for mould growth, leading to potential occupant health impacts if mould spores transfer into living spaces above. A direct comparison could not be made between insulated and uninsulated floors in the sample due to non-random sampling and because the insulated floors included historically damp floors. The study also highlighted that long-term monitoring over all seasons and high-resolution monitoring and inspection are required; conditions in one location are not representative of conditions in other locations.
Value: This study presents the largest UK sample of monitored floors, evaluated using a review of current evidence and comparison with literature thresholds.
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This research was funded by the EPSRC Centre for Doctoral Training in Energy Demand (LoLo), grant numbers EP/L01517X/1 and EP/H009612/1 while the corresponding author was at UCL. The authors are also very grateful for the support of: the Belgian Chair Charity Fund administered by the Embassy of Belgium in London, to the homeowners for access to the case study houses and to Salford City West Housing Association, Carbon Co-op, NBT, Knauf, Energy Savings Trust and Downs Energy for support of the studies at different stages.