SINTEF/NTNU projects - snapshots for the LBNL Window group

submittedVersio

The European and Norwegian market for window technology

acceptedVersio

Montana Kaimin, September 27, 2001

Student newspaper of the University of Montana, Missoula

Rain-tightness of door sill sealing

The harsh Norwegian climate requires buildings designed according to high standards. The airtightness of the building envelope is crucial to attain an energy efficient building and to avoid moisture problems. A considerable part of building defects registered in the SINTEF Building defects archive are related to leakages through door sills especially in combination with balconies. The aim of the study has been to examine the rain tightness of the joint below door sills. A laboratory investigation using a driving rain cabined according to EN 1027 has been conducted to provide answers to the matter. In total 14 different test were conducted. Two different sills were included, both a traditional high sill and a lower handicap-sill. Two different underlays for the sill were included in the investigation. In addition, 3 different heights of the joint-sealing below the sill were chosen (0, 5 and 10 mm). All the tests except two were performed with silicon as joint sealant material. It was found that the workmanship of the joint-sealing was challenging due to the geometry of the detail. Even if the silicon sealant was carefully applied, voids between the sealant and door sill were found when inspecting closely. When improving the faults, the test showed that the joints was tight. 11 of the 14 tests showed no water leakages at 600 Pa pressure difference. However, leakages were observed at lower pressure differences for the sills with no silicon sealing and for the configurations where there were faults in the silicon sealing. The laboratory study revealed that the joint below the door sill is vulnerable to small mistakes in the workmanship. Given a carefully application and control of the silicon sealing it is possible to achieve a high water tightness performance. However, improvements to the sealing detail is needed to further increase the robustness of the detail

Solar efficiency index of building envelopes and load matching in low energy buildings

Net-zero energy buildings oftentimes rely on solar-based building integrated technologies to offset energy use and achieve their goals. However, the value of a particular system is difficult to assess given that these technologies often bring about complex interactions with the indoor environment, and building energy management systems. The approach chosen in this study was to propose and test a simple index called the Solar Efficiency index (SE index), which makes it possible to characterize the performance of building envelopes with integrated solar systems. The index was used to investigate the effect of different configurations of a PV integrated shading device on an office building in Norway. The results provided by the index allowed estimating how much solar energy was converted and how useful that energy was to the building in terms of load matching. This provided a picture of the building’s energy autonomy

Numerical investigation of a diffuse ventilation ceiling system for buildings with natural and hybrid ventilation

The need to meet requirements, both in terms of ventilation and thermal comfort in modern buildings, has led to the development of different concepts for ventilation, among which the so-called Diffuse Ceiling Ventilation (DCV). This system makes use of the space between the ceiling slabs and the suspended ceiling as a plenum for fresh air, while the suspended ceiling itself becomes an air diffuser element. If compared to traditional solutions, this allows a higher amount of ventilation air to be injected in the room at lower speed, and a more even distribution of the fresh air within the room. Furthermore, it allows an easy integration with sound-absorbing perforated ceiling panels, since their typical design makes them particularly fit to be used as air diffusers. This paper builds upon a previous work by the authors where CFD simulations were used to optimise the dimension and the distribution of the perforation pattern in the panels to achieve an even air speed distribution. In this work, the performance of the perforated ceiling is investigated in a more comprehensive way, evaluating the thermal comfort in the room when varying the outdoor temperature. This solution is in fact meant to work in combination with natural or hybrid ventilation strategies, where the fresh air flow is supplied from the façade. Numerical simulations were performed on a typical office room, considering both the winter and the summer season, for different inlet air temperatures. This solution demonstrated a positive impact on the indoor conditions and on the thermal comfort inside the room in most of the cases but the most extreme ones. The thermal stratification in the room demonstrated to remain within a satisfactory level

Moisture robustness of eaves solutions for ventilated roofs – experimental studies

Ventilated pitched wooden roofs with eaves (roof overhangs) is a common building practice in the Scandinavian countries. The eaves are protecting the façade from rain, wind driven rain (WDR) and snow, and it covers the roof ventilation aperture. The eaves should be designed so that the least possible amounts of rainwater and snow enters the ventilation aperture between the roof cladding- and underlayer roofing. At the same time, adequate ventilation of the roof must be ensured to promote proper drying-out capabilities of the roof and to avoid problems of snow melt and ice formation at eaves and gutters during winter season. Small or almost nonexisting eaves is a trend in modern architecture. It is a common perception that such solutions are more vulnerable to moisture damages due to possible increase of water penetration into the roof aperture. The aim of the study is to experimentally investigate the moisture robustness of the described risk area and to find answers to how the design of eaves influence the amount of rain that is driven on to the underlayer roofing under the aperture in ventilated roofs. It was found that the amount of collected water in the different test series to a large extent are given by the water droplet size as well as the wind velocity inside the air cavity. The results from this study simulates an example of a rain event with heavy rain intensity and strong winds (storm). The test represents an example of a storm event with a given droplet size distribution. The results indicate that an increased pressure drop decreases the water ingress. Comparative tests showed that installation of a wire mesh largely decreases the measured water collection and the dynamic pressures inside the air cavity

Phase Change Materials in Glazing: Implications on Light Distribution and Visual Comfort. Preliminary Results

The visual comfort concerned with a technology with PCM embedded into a double glazing unit was analyzed, using the Daylight Probability Glare and the ‘Useful Illuminance’ (percent of workplane with an illuminance in the range 100-3000 lx). A sample office room was modeled using Radiance, under a clear sky and with the façade facing south. The visible transmittance of PCM was measured in laboratory and used as input in Radiance. The simulations were carried out for the two solstices and the Autumn equinox (four hours per day), for three sites (Östersund, 63.2°N; Turin, 45.2°N; Abu Dhabi, 24.4°N), considering the solid state of the PCM only