10:30am - 10:45am
Internal Insulation of preservation worthy facades
1Saint-Gobain Denmark ISOVER, Denmark; 2Technical University of Denmark, Denmark; 3Hygge Engenharia
With international awareness of the need to decrease greenhouse emissions, the Danish government set a target to be fossil fuel free by 2050. In order to achieve this, existing buildings will need to be retrofitted with energy saving technologies such as improved thermal insulation.
In Denmark a larger mass of the building stock from around 1850 to 1940s is preservation worthy. The construction is typically solid brick walls with wooden beams in the floors. This creates a challenge for energy retrofitting since the external facades cannot be altered.
The application of internal insulation can influence the temperature and moisture profile of the wall. This can become an issue in these preservation worthy buildings. Moisture build up in the interface between the original brick wall and insulation layer can create an environment where mold can grow. Previous research also demonstrated that there is risk of moisture build up at the beam-ends when internal insulation is applied. Although there are a number of products on the market for internal insulation, no completely safe solution has been identified.
Saint-Gobain ISOVER has together with DTU spent the last 5 years developing a new system, ISOVER RetroWall System, which addresses to these problems. The unique feature of the RetroWall is the inclusion of a dehumidifier system which dehumidify an airspace between the original wall and the insulating wall. This prevents the build-up of moist that can lead to problems with mold and rot in the existing construction.
In order to finalize the system field test over 2 years on 4 building sites and 3 master thesis on moisture behavior, airflow and sound reduction has been done.
The presented work will include a short introduction to the concept, results and conclusions from the field test and presentation of two sites with the finished system in use.
10:45am - 11:00am
Assessing the building envelope performance of a renovated historical dwelling using a coheating test
1Department of Architecture and Urban Planning, Ghent University, Belgium; 2Department of Flow, Heat and Combustion Mechanics, Ghent University, Belgium
As part of a Flemish research project, twelve quasi-identical almshouses of a small residential quarter in the historic city centre of Bruges were renovated. These houses date from 1908 and were refurbished to a limited extent in the 1990s. Besides a social-cultural value, this former almshouse complex also has an artistic and architectural-historic value. Consequently, it is protected as a monument. However, a renovation was needful because of the high energy use, the poor indoor comfort and the numerous moisture problems.
A balance had to be found between hygrothermally upgrading the uninsulated building envelope, limiting the loss of living space in these very small houses and properly respecting the historical heritage preserving the monumental character of the façades in their original state. Therefore innovative insulation materials with a very limited spatial impact were used. The floor was insulated with vacuum insulated panels, aerogel plaster was applied to the interior side of the walls and the windows were replaced by new wooden frames with thin double glazing.
Several quality assurance tests were executed. The thermal conductivity of three samples of aerogel plaster were determined using the guarded-hot-plate method and compared with the stated performance in the technical documentation. Furthermore, an in-situ heat flux measurement on the exterior wall and several blowerdoor tests were performed both before and after renovation to estimate respectively the actual thermal transmittance of the masonry wall and the air change rate n50 of the building envelope. Thirdly, during three weeks a coheating test was executed in a renovated dwelling. The measurement results of this test were analysed using linear regression analysis and assumption testing to determine the heat loss coefficient of the building. This made it possible to evaluate the quality of the renovation and to compare the results with the initial theoretical design calculations.
11:00am - 11:15am
Recent progress of the SPIDER – project: Aspects of subtractive approaches to existing building’s performance improvement
1University of Applied Arts Vienna, Austria; 2TU Wien, Austria
This contribution reports about methodology, progress and preliminary findings of a recent exploratory Research and Development project, pertaining to the (Semi-) automated thermal retrofit of existing building’s envelopes. Thereby, the potential of robots, which autonomously identify areas of facades that can be used for inserting openings into the existing wall material, is examined. The idea is based on the fact that masonry walls of historic masonry walls (especially of Gründerzeit buildings built between 1850 and 1918) often have been structurally over-dimensioned. As such, the spare thickness of the walls could be used for thermal insulation purposes. The idea to implement air cavities for insulation purposes is in correspondence with the predominant functional principle of most insulation materials. A number of conditions needs to be fulfilled so that such a robot-based approach could be successful: (i) A comprehensive digital representation of the façade that should be retrofitted is required. This representation should allow the easy identification of areas where robots can refit the façade, and areas that are not suitable for such interventions due to structural, aesthetic or other reasons. (ii) the Thickness, form, and potential re-closing of drilled openings have to be carefully explored; (iii) Robotic technologies need to be identified that allow the autonomous climbing of drilling robots on the façade surface. Moreover, the robots require interfaces to the mentioned façade representation, allowing them to navigate on the façade, determine critical areas, and to apply the correct retrofit measure at the correct position (iv); Economic, organizational, and technological aspects of retrofit works carried out by robots need to be clearly determined.
Needless to say, the idea of subtractive insulation by autonomous robots is its early technology readiness levels. However, the present contribution provides some fundamental insights into the implications of the approach.
11:15am - 11:30am
Desalination using clay and lime sacrificial plasters with additives on field stone wall and fired clay bricks
Estonian University of Life Sciences, Estonia
Salt damage can ruin the appearance and destroy the structure of buildings and statues. To prevent this, there exist passive methods that stop the water intake and active methods to extract salts from the structure. Common active methods include sprinkling water on the structure, scraping off the concentrated salts from the surface and the use of sacrificial plaster. For desalination sacrificial plasters are traditionally used. In order to determine which desalinating plaster is more effective and also easy to remove, two sites were used. The first test was done on a two hundred years old stable wall in Mooste county Estonia. Salt percentage by mass in the test wall was determined in 2017. In December 2019 five different sacrificial plasters were tested on the wall using local natural plaster clay and lime with additives hemp flax, charcoal and turf. The second test was done with fired clay bricks that were placed into the salt solution until the efflorescence appeared. In the desalination process, nine sacrificial plasters based on clay and lime were used (five of them identical with the field test, plus clay and lime plaster without any additives and plaster with smectite additive). After removing the sacrificial plaster, samples were drilled from the mortar and the bricks to measure salt content by Ion chromatography. Sacrificial plasters made from clay and hemp flax were the most suitable for desalination and removal.
11:30am - 11:45am
Heating the Dutch housing stock without natural gas
TNO, Netherlands, The
In the coming years, the Dutch housing stock will have to be made more sustainable in order to meet climate targets. Furthermore, the Dutch government strives for an energy supply without natural gas, using instead district heating networks at lower supply temperatures and heat pumps. Low temperature heating networks allow for a wider use of alternative heat sources such as industrial waste heat or geothermal energy.
The research question is to what level the Dutch housing stock needs to be improved for an energy supply without natural gas. In answering the question, we focused on space heating, leaving DHW and cooling demand out of the scope.
First, an inventory was made of common types of single family dwellings in the Netherlands. For each type (35 in total), a dwelling was visited by an energy adviser, noting the characteristics of the dwelling and (energy related) user behaviour through a questionnaire.
Using a dynamic building model, annual heating demand was calculated for each dwelling, taking specific user behavior into account. The results agreed well with the actual gas consumption.
Three renovation packages of increasing level of ambition were composed. As additional measures, heat recovery in the ventilation system and increased airtightness were considered. Using the model, annual heating demand and hourly thermal powers were calculated for each dwelling fitted with the three renovation packages. This allowed us to assess whether the dwellings with these renovation packages can be kept warm throughout the year when using a heat supply at lower temperature.
The energy savings were compared to the cost of the renovation packages, yielding a simple payback time. An overall assessment of the packages was made using the required thermal power, energy savings and payback time as criteria.