C-MADE - Centre of Materials and Building Technologies

This paper presents some of the findings of a wider study on a ventilated double
window as a system to pre-heat the ventilation air. The study focused on the design aspects of
this system as a function of airflow pattern generated by stack and wind effect. Experimental
measurements of the thermal performance of the ventilated double window were carried out in
an outdoor environment in the winter season. In the experiments, the outside and inside temperatures,
the airflow rate and also the temperatures distribution along the window ventilated
cavity were measured every minute. In this paper, some of the experimental results are presented.
Field results from this study are expected to help designers to conceive ventilated double
windows duly adapted to local climate where ventilation is an important design consideration
and heat loss must be reduced. The tested system proved to be able to contribute significantly
for this reduction.

This paper compares several different simplified methodologies for building energy performance assessment during winter time selected based on its large application and/or its user friendly characteristics. Hourly values for energy demand are calculated by a detailed comparison tool based on hourly weather data. A simplified building procedure spreadsheet to evaluate energy demand is also presented. It gives reliable results, needs only a little input data to describe the building design and low time consumption. The spreadsheet is therefore useful for preliminary design tasks in the early design stages where rough estimates of the building design and preliminary energy use are needed for primary decision support. The method is based on a seasonal heating calculation of heat losses and usable heat gains for the building, where the heat-accumulating capacity of the building is considered. The seasonal mean values of the solar radiation and degree days are applied. This paper describes the applied calculation technique and the assumptions made to carry out heating calculation.

A study on thermal retrofit of Portuguese elementary school buildings is presented. The type of school under analysis is one adopted by a large construction campaign that began in the 1940's. This building stock has a very poor thermal performance and their retrofit was evaluated starting with a case study of a school in the central region of Portugal, where some experimental measures were performed and a calculation method was applied for the heating energy consumption estimation. A solution for the thermal retrofit of the school building external envelope was optimized and the effect on heating energy consumption was evaluated, using ECOTECT, resulting in a reduction of 52% of heating energy needs. The national impact of the thermal retrofit of the whole building stock was characterised in terms of energy savings. Finally, the pre‐heating of the ventilation air was also tested as a complementary measure and its effect evaluated. The solution tested may provide up to 1000 kWh/year of extra heat gains by pre‐heating the ventilation air. It must be underlined though that the performance of these systems is dependent on the thermal properties of their components so higher reductions can be achieved with the improvement of these properties.Straipsnyje pateikiami Portugalijos pradines mokyklos šiluminio atnaujinimo tyrimai. Analizuojamos mokyklos tipas yra vienas iš taikytu po 1940 metu prasidejusioje plačioje statybos kampanijoje. Šios pastatu grupes šilumines charakteristikos yra labai prastos. Ju atnaujinimo vertinimas buvo pradetas nuo centrineje Portugalijoje esančios mokyklos, kurioje buvo igyvendintos kai kurios eksperimentines priemones, ir energijos sanaudoms nustatyti pritaikytas skaičiavimo metodas. Pastato išoriniu atitvaru šiluminio atnaujinimo sprendimas buvo optimizuotas ir jo itaka šilumines energijos sanaudoms nustatyta naudojant ECOTECT. Šilumines energijos poreikis sumažejo 52 %. Iš viso pastatu fondo šiluminio atnaujinimo itaka nacionaliniu mastu vertinta sutaupytos energijos kiekiu. Pabaigoje kaip papildoma priemone buvo išbandytas pirminis vedinamo oro pašildymas, nustatytas jo naudingumas. Išbandytasis pirminis vedinamo oro pašildymas gali suteikti iki 1000 kWh/metus papildomo išsiskiriančio šilumos kiekio. Pabrežtina, kad nors šiu sistemu veikimo charakteristikos priklauso nuo ju komponentu šiluminiu savybiu, gerinant šias savybes galima daugiau sumažinti energijos sanaudu.

The energy efficiency of a building is determined by a set of environmental, technical and usage factors. By integrating the building into the surrounding environment and incorporating efficient technologies into the construction the design will contribute to overall goals. This can include the adoption of certain strategies like the implementation of natural ventilation, effective shading, the construction of sunspaces, thermal storage walls or other passive solutions, the use of solar collectors, etc. One of those strategies is the pre-heating of ventilation air and a variety of technical solutions have been studied and tested in order to compensate for thermal losses due to air renovation. The incoming air is pre-heated passively before entering indoors. For this purpose one can use an earth-to-air heat exchanger, enclosed spaces, solar collectors or different kinds of transparent facades. Recently, a study was carried out at the University of Beira Interior, Portugal where a double ventilated window was tested under real outdoor conditions. This passive heating system derived from the double window system that is currently adopted in Portuguese residential buildings to prevent air leakage and thermal discomfort. Simple changes were made by introducing vents at the base of the outer window and at the top of the inner window to allow a supply of fresh air through it. The air coming from the outside rises through the channel between windows, due to wind pressure and stack effect. The air is pre-heated by the heat that escapes from inside through the inner window and by the incident solar radiation before entering the building acting as a heat exchanger. Experimental studies show that this technique is capable of supplying air to the interior of the building at a higher temperature than the air outside. In this paper, some of the experimental results are presented. A parametric analysis was also carried out to determine the performance of this passive heating system. It took into account the physical phenomena of heat and mass flow processes and also geometric and boundary conditions. This low cost building technology can be implemented in new and existing buildings and proved to be effective in reducing heating energy consumption. Field results from this study are expected to help designers to conceive ventilated double windows duly adapted to local climate where ventilation is an important design issue and heat loss must be reduced.

The Monastery of Our Lady of Nazareth of Mocambo in Lisbon, usually known as Bernardas’ Convent, was a Cistercian foundation. After the extinction of the religious orders, in 1834, the Monastery had several uses. As the building had to be preserved under historical regulation its unchanged exterior walls are made of solid masonry which dominates construction throughout the history. The historic building has also been experiencing a change in indoor climate due to the higher standards of comfort that are required. Although the function of the walls is primarily structural as well as durable and weather resistant, other performance requirements such as sound penetration resistance, fire resistance and energy efficiency must now be fulfilled. This paper aims to discuss and to explore factors of city growth and cultural development.

Throughout human history the "green" element has always been present. The gardens comprised many purposes, as sacred spaces, leisure, cure; as architectural elements which characterized outdoor spaces; were also an experimental field. Buildings acquire a vegetable aesthetic language with the dawn of Jugendstil and Art Nouveau. Through ecological theories artists, as Hundertwasser emerge, and manifestos for the use of “green” by architecture and the city were written. Through the end of the 20th century and early 21th century the acquired garden concept has been challenged. The horizontal roof was then an experimental ground on which architecture could respond to a new challenge: the green facades or vertical gardens. New architectural elements are created which adverse
environmental conditions are mitigated, either on new construction or on architectural rehabilitation. In the C-MADE,
at the UBI, the GEOGREEN research project in this field is being carried out supported by FCT.

Keeping the indoor air quality within the reference levels requires that the polluted indoor air be replaced by fresh air coming from the outside. This paper presents a sensitivity analysis and a series of simulations where the performance of this passive system is studied. The influence of each relevant factor, like the wind, the solar radiation, and the outdoor air temperature, is assessed. Two different local sets of climatic data were chosen, a mild and a cold winter.