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Full-scale studies of improving energy performance by renovating historic Swedish timber buildings with hemp-lime

Strandberg-de Bruijn, Paulien LU ; Donarelli, Anna and Balksten, Kristin (2019) In Applied Sciences (Switzerland) 9(12).
Abstract

With an increased focus on reducing greenhouse gas emissions, energy saving is of great importance in all sectors of society. EU directives set targets for member states to reduce energy use in buildings. Energy saving in historic buildings requires special measures, balancing energy-saving renovations against the preservation of heritage values. Traditional constructions are open to vapor diffusion and generally work differently from modern constructions. Modern materials in traditional constructions sometimes damages the original material as they are usually diffusion-tight. The aim of this study was to investigate whether hemp-lime could be used as an insulation material to improve the energy effciency of historic timber building... (More)

With an increased focus on reducing greenhouse gas emissions, energy saving is of great importance in all sectors of society. EU directives set targets for member states to reduce energy use in buildings. Energy saving in historic buildings requires special measures, balancing energy-saving renovations against the preservation of heritage values. Traditional constructions are open to vapor diffusion and generally work differently from modern constructions. Modern materials in traditional constructions sometimes damages the original material as they are usually diffusion-tight. The aim of this study was to investigate whether hemp-lime could be used as an insulation material to improve the energy effciency of historic timber building envelopes with a rendered façade in Sweden. The objective was to determine the actual energy savings for space heating. An additional objective was to determine the actual thermal transmittance and to study thermal buffering through in-situ measurements in a full-scale wall renovated with hemp-lime. Two full-scale wall sections were constructed at the Energy and Building Design laboratory at Lund University: A traditional post-and-plank wall with a lime render (80 mm), and a post-and-plank wall with a hemp-lime render (90 mm). Energy use for space heating was monitored continuously over a period of one year. The wall with a hemp-lime render required 33% less energy for space heating than the traditional post-and-plank wall with a lime render. This was accomplished without changing the framework, appearance or material in the render and without drastically changing the hygric properties of the façade. From the gathered data, the thermal transmittance (U-values) for both walls was calculated using two different methods, one based on material properties and the other based on energy use data. For both walls, thermal transmittance based on actual energy use data during the heating period was lower than what was expected from their material properties. This indicates that more material properties than thermal conductivity and material thickness need to be taken into account when performing energy use calculations. With hemp-lime, a renovation can be accomplished without damaging the timber structure and wooden slats, and it can be done with local traditional materials and building methods with no difference in appearance to a traditional lime render. This allows for heritage values to be preserved, while also allowing the building to comply with modern standards and with increased thermal comfort and reduced energy use.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cultural heritage, Energy effciency, Hemp-lime, Lime render, Retrofitting, Thermal insulation
in
Applied Sciences (Switzerland)
volume
9
issue
12
publisher
Multidisciplinary Digital Publishing Institute (MDPI)
external identifiers
  • scopus:85068135811
DOI
10.3390/app9122484
language
English
LU publication?
yes
id
b494a40f-18c1-41dd-b169-33f2cb1033c7
date added to LUP
2019-07-09 16:15:46
date last changed
2019-08-06 03:24:01
@article{b494a40f-18c1-41dd-b169-33f2cb1033c7,
  abstract     = {<p>With an increased focus on reducing greenhouse gas emissions, energy saving is of great importance in all sectors of society. EU directives set targets for member states to reduce energy use in buildings. Energy saving in historic buildings requires special measures, balancing energy-saving renovations against the preservation of heritage values. Traditional constructions are open to vapor diffusion and generally work differently from modern constructions. Modern materials in traditional constructions sometimes damages the original material as they are usually diffusion-tight. The aim of this study was to investigate whether hemp-lime could be used as an insulation material to improve the energy effciency of historic timber building envelopes with a rendered façade in Sweden. The objective was to determine the actual energy savings for space heating. An additional objective was to determine the actual thermal transmittance and to study thermal buffering through in-situ measurements in a full-scale wall renovated with hemp-lime. Two full-scale wall sections were constructed at the Energy and Building Design laboratory at Lund University: A traditional post-and-plank wall with a lime render (80 mm), and a post-and-plank wall with a hemp-lime render (90 mm). Energy use for space heating was monitored continuously over a period of one year. The wall with a hemp-lime render required 33% less energy for space heating than the traditional post-and-plank wall with a lime render. This was accomplished without changing the framework, appearance or material in the render and without drastically changing the hygric properties of the façade. From the gathered data, the thermal transmittance (U-values) for both walls was calculated using two different methods, one based on material properties and the other based on energy use data. For both walls, thermal transmittance based on actual energy use data during the heating period was lower than what was expected from their material properties. This indicates that more material properties than thermal conductivity and material thickness need to be taken into account when performing energy use calculations. With hemp-lime, a renovation can be accomplished without damaging the timber structure and wooden slats, and it can be done with local traditional materials and building methods with no difference in appearance to a traditional lime render. This allows for heritage values to be preserved, while also allowing the building to comply with modern standards and with increased thermal comfort and reduced energy use.</p>},
  articleno    = {2484},
  author       = {Strandberg-de Bruijn, Paulien and Donarelli, Anna and Balksten, Kristin},
  keyword      = {Cultural heritage,Energy effciency,Hemp-lime,Lime render,Retrofitting,Thermal insulation},
  language     = {eng},
  month        = {06},
  number       = {12},
  publisher    = {Multidisciplinary Digital Publishing Institute (MDPI)},
  series       = {Applied Sciences (Switzerland)},
  title        = {Full-scale studies of improving energy performance by renovating historic Swedish timber buildings with hemp-lime},
  url          = {http://dx.doi.org/10.3390/app9122484},
  volume       = {9},
  year         = {2019},
}