Evaluating building envelopes for energy efficient buildings : Energy- and moisture performance considering future climate change
(2013)- Abstract
- Buildings account for a signifi cant proportion of the energy use that
generates greenhouse gases and consequently drives the ongoing climate
change. As the population of the world increases, the need for buildings
increases, while the energy use needs to decrease. A reduction in energy
use and increased use of renewable energy are important measures for
climate change mitigation. A fi rst step in decreasing the energy use of a
building in a Nordic climate is to increase the thermal resistance of the
building envelope.
The combination of climate change and more insulation in building
elements will result in a different microclimate within the building elements. External parts in well-insulated building... (More) - Buildings account for a signifi cant proportion of the energy use that
generates greenhouse gases and consequently drives the ongoing climate
change. As the population of the world increases, the need for buildings
increases, while the energy use needs to decrease. A reduction in energy
use and increased use of renewable energy are important measures for
climate change mitigation. A fi rst step in decreasing the energy use of a
building in a Nordic climate is to increase the thermal resistance of the
building envelope.
The combination of climate change and more insulation in building
elements will result in a different microclimate within the building elements. External parts in well-insulated building envelopes will have a
microclimate more similar to the exterior climate as the thermal resistance
increases and moisture may take a longer time to dry out.
Today, there are several established ways to calculate and quantify the
energy performance of buildings and building components. As regards
calculation of transmission heat transfer through building envelopes, there
is a lack of knowledge among Swedish engineers and architects. There
are ambiguities regarding the defi nition of a thermal bridge and the way
building elements are quantifi ed in energy calculations.
There are models to quantify the moisture performance of a building
element, where the focus is to evaluate the risk of mould growth. Regarding other moisture-related problems, such as corrosion, deformations etc.,
critical moisture levels are established. However, these levels are not valid
for short-term loads. Only models of mould growth take into account
fl uctuations in hygrothermal conditions.
Traditionally, durability and robustness of building elements are based
on experience and are not specifi ed in quantitative terms. However, increasing the thermal resistance in combination with climate change will result in
different hygrothermal conditions within the building envelope. Building
elements needs to be designed with reference to these aspects.
To enable evaluation of energy- and moisture performance, which
are presented in dissimilar units, a model has been developed in order to
present a weighted value which includes both aspects. The model includes
Evaluating building envelopes for energy effi cient buildings
4
a performance failure indicator that ensures that the weighted value of
an evaluation is unacceptable if any of the evaluated indicators are below
acceptable level. This means that it is not possible to compensate for the
poor performance of one indicator by achieving a very high value for
another indicator.
Initial tests have been conducted by using the model to evaluate a limited part of a building envelope, but also for a whole building. The tests
of the model showed that it is possible to handle a large set of criteria and
to weight them into one value.
Future work in this project will investigate building envelopes in order
to indicate measures that could have a large effect on the transmission
heat transfer losses. Furthermore, additional work to investigate future
climate scenarios and improvement of the usability of the model will be
performed. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1277afea-cb36-4a4d-a9a7-e30c983caa68
- author
- Berggren, Björn LU
- supervisor
- organization
- publishing date
- 2013-04-01
- type
- Thesis
- publication status
- published
- subject
- language
- English
- LU publication?
- yes
- id
- 1277afea-cb36-4a4d-a9a7-e30c983caa68
- date added to LUP
- 2022-01-20 12:43:58
- date last changed
- 2023-04-18 17:15:35
@misc{1277afea-cb36-4a4d-a9a7-e30c983caa68,
abstract = {{Buildings account for a signifi cant proportion of the energy use that<br/>generates greenhouse gases and consequently drives the ongoing climate<br/>change. As the population of the world increases, the need for buildings<br/>increases, while the energy use needs to decrease. A reduction in energy<br/>use and increased use of renewable energy are important measures for<br/>climate change mitigation. A fi rst step in decreasing the energy use of a<br/>building in a Nordic climate is to increase the thermal resistance of the<br/>building envelope.<br/>The combination of climate change and more insulation in building<br/>elements will result in a different microclimate within the building elements. External parts in well-insulated building envelopes will have a<br/>microclimate more similar to the exterior climate as the thermal resistance<br/>increases and moisture may take a longer time to dry out.<br/>Today, there are several established ways to calculate and quantify the<br/>energy performance of buildings and building components. As regards<br/>calculation of transmission heat transfer through building envelopes, there<br/>is a lack of knowledge among Swedish engineers and architects. There<br/>are ambiguities regarding the defi nition of a thermal bridge and the way<br/>building elements are quantifi ed in energy calculations.<br/>There are models to quantify the moisture performance of a building<br/>element, where the focus is to evaluate the risk of mould growth. Regarding other moisture-related problems, such as corrosion, deformations etc.,<br/>critical moisture levels are established. However, these levels are not valid<br/>for short-term loads. Only models of mould growth take into account<br/>fl uctuations in hygrothermal conditions.<br/>Traditionally, durability and robustness of building elements are based<br/>on experience and are not specifi ed in quantitative terms. However, increasing the thermal resistance in combination with climate change will result in<br/>different hygrothermal conditions within the building envelope. Building<br/>elements needs to be designed with reference to these aspects.<br/>To enable evaluation of energy- and moisture performance, which<br/>are presented in dissimilar units, a model has been developed in order to<br/>present a weighted value which includes both aspects. The model includes <br/>Evaluating building envelopes for energy effi cient buildings<br/>4<br/>a performance failure indicator that ensures that the weighted value of<br/>an evaluation is unacceptable if any of the evaluated indicators are below<br/>acceptable level. This means that it is not possible to compensate for the<br/>poor performance of one indicator by achieving a very high value for<br/>another indicator.<br/>Initial tests have been conducted by using the model to evaluate a limited part of a building envelope, but also for a whole building. The tests<br/>of the model showed that it is possible to handle a large set of criteria and<br/>to weight them into one value.<br/>Future work in this project will investigate building envelopes in order<br/>to indicate measures that could have a large effect on the transmission<br/>heat transfer losses. Furthermore, additional work to investigate future<br/>climate scenarios and improvement of the usability of the model will be<br/>performed.}},
author = {{Berggren, Björn}},
language = {{eng}},
month = {{04}},
note = {{Licentiate Thesis}},
title = {{Evaluating building envelopes for energy efficient buildings : Energy- and moisture performance considering future climate change}},
url = {{https://lup.lub.lu.se/search/files/112262248/Webb_lic_avhandl_BB.pdf}},
year = {{2013}},
}