- Na imagem abaixo têm alguns equipamentos HRU certificados:Eu estou interessada nisto:
http://ochsner.com/
em especial as Europa e, mais especialmente, a Mini WIP (porque me daria jeito ter a bomba separada do depósito de água). Ao que parece, é adequada a casas passivas, por exemplo. Vi num catálogo estrangeiro que custa cerca de 2000€ e mandei um mail para a climaconforto a perguntar se têm, e por que preço.
A propósito de janelas, tenho a dizer que acho as janelas de vidro duplo portuguesas uns bacamartes comparados com muitas das que se usam em França ou na Bélgica. Provavelmente é um exagero.Esses 200mm a 300mm são um exagero... Quer na quantidade de esferovite, que nas adaptações que tem que fazer para utilizar um sistema desses.
Apenas um pequeno exercicio. Se quisesse meter uma cantaria (soleira ou peito), teria que contar com 22 cms para alvenaria + 3 cms para estuques interiores + 20cms para EPS. Daria uma cantaria de 45 cms... embora seja perfeitamente possível, é um exagero... tal como será depois na profundidade das janelas, nas semalhas dos telhados, etc...
Segundo o LNEC, com EPS de 60 mm consegue-se a melhor relação preço qualidade.
Coisas da Casa- J.Fernandes
- 7 julho 2009
Em vez de estar a pensar em 200mm de EPS de isolamento por fora, não será mais racional e mais eficiente fazer um isolamento pelo exterior de 40mm de EPS e outro pelo interior, com a mesma espessura, coberto, por exemplo, por uma parede de Pladur? Não será uma solução muito mais equilibrada entre isolamento e inércia térmica?Ou então optar por uma alvenaria com características térmicas superiores!!
Coisas da CasaGostava de saber qual seria o aumento de conforto se se fizesse simplesmente janelas (e portas) de madeira (ou PVC), bem vedadas e sem frinchas, sem mais flores. Provavelmente seria suficiente para uma boa parte de Portugal, pelo menos se se acrescentasse um bom isolamento das coberturas.Ou então optar por uma alvenaria com características térmicas superiores!!
Poderia apontar alguns exemplos? Ou mencionar as características térmicas entre os vários tipos de alvenaria?
ObrigadoColocado por: lfdBoa tarde,
Ok, então agora a minha questão é: como é que posso fazer isto, cá em Portugal?
Cumprimentos
Por acaso há quem o tenha feito em Portugal, uma passive house, um casal de Sul Africanos, na restauração de uma casa no Algarve. Tenho a revista, Casas de Portugal, onde vem apresentada essa casa. Se quiser posso ver mais pormenores (nome da casa e/ou dos proprietários e pode ser que através deles, consiga saber mais).
Cumprimentos,,A digitalização e upload desse artigo era bem vinda :)Acabei de encontrar este site com links bastante interessantes (nomeadamente para casas já construídas), que ainda não tive tempo de explorar:
http://arquitecologia.org/Colocado por: electraoA digitalização e upload desse artigo era bem vinda :)
Vou fazer. Em breve coloco aqui (amanhã(?)).Aqui está o tal artigo : "Metamorfose da Velha Ruína" do nr 85 da revista Casas de Portugal.
A parte mais relevante para esta discussão será a partir da página 4, especialmente os entitulados "Avançar a pouco e pouco" e "Ar condicionado natural", embora o artigo seja interessante no todo (tratando-se de uma restauração e recuperação de uma ruína).
(Tive que dividi-lo em 5 partes por causa do tamanho, que no Forum não permite mais do que 512KB)
Cumprimentos,Páginas 2 e 3E cá estão a página 4
e a 5Achei que este texto expõe duma maneira muito clara a questão da transferência do conceito de passivhaus para os paises dos sul da Europa:
http://www.passive-on.org/en/downloads/Marketable_Passive_Homes_for_the%20Mediterranean.pdf-
Pedro Barradas
- 10 julho 2009 editado
Ficheiro da Velha ruina, reunido num so ficheiro...Estou a tentar encontrar docs sobre o tipo de tecnologia mencionado no artigo: "sistema de alta tecnologia baseada no arrefecimento por evaporação. Colocaram esse sistema em cima da torre, permitindo assim um fluxo constante de ar filtrado, humidifcado e refrescado para todas as partes da casa.".
Se alguém encontrar mais material explicativo deste tipo de sistema, favor por link ou fazer upload.
Já encontrei um, mas ainda estou a digerir-lo:
EVAPORATIVE COOLING METHODS
When water evaporates it absorbs a large amount of heat from its surroundings (about 1000 BTU per pound of water evaporated). The most familiar example of this is the cooling effect of evaporating perspiration on the human skin. In arid, hot climates body temperature is partially controlled by the rapid evaporation of perspiration from the surface of the skin. In hot climates with high atmospheric moisture the cooling effect is less because the high moisture content of the surrounding air. In both situations, however, the evaporation rate is raised as air movement is increased. Both of these facts can be applied to natural cooling of structures.
Evaporative methods can be used to enhance the cooling rates in convective cooling systems. One way of doing this is to bring the outdoor air into the house through a moist filter or pad as shown in Figure 28. The familiar evaporative cooler, precursor to the air conditioner, is a mechanical system which uses these principles with a motor to force air movement and distribution. Passive cooling strategies with earth tubes and/or cool towers use the same principles but utilize natural systems for air drivers and distribution. If underground intake pipes are made from a porous material, and ground above them is well cool and watered, some evaporation will occur at the inner surface of the pipe.
Cool towers utilize wet cooling pads, and the force of gravity. Heavier, cooled air "falls", via gravity, into the building and its momentum floods the habitable area. This cool tower action, as well as that of the earth cooling tubes, can be enhanced and distribution extended, by the placement of thermal chimney "drivers" which can pull the cooled air through the building with an increase in both air quantity and velocity. In either case, the cooler air now has a higher relative humidity, but this is not usually a problem and can even be a benefit in arid climates.
In some areas, there may be a time of higher humidity (desert monsoon season). While sensible heat continues to be mitigated by passive cooling techniques, the latent heat contained in the humid air is more difficult to dissipate, which renders evaporative cooling less effective. The integration of a air dehumidification system easily corrects this short term problematic condition.
Evaporative cooling strategies are well suited to those areas of the southwest with the most severe cooling requirements. In the desert areas of the South, the warm night air (80 degrees+) may impede natural convection heat dissipation from a roof pond cooling system. That is one of the reasons why the cooling rate falls to about 25 BTU/hr/ft^2 in the extreme southeast corner of the state (Fig. 29). Simple introduction of a thin water layer over the water containment surface can increase the overall cooling rate of the roof by 50-100 percent due to the resulting evaporation.
In the most severe climates where nighttime air temperatures often remain above 90°F in summer, sprays can be used to achieve maximum natural cooling, at standard roofs and roof cooling systems like the roof pond strategy. In the summer, sprays can be used to achieve optimum natural cooling. In the approach shown in Figure 30, water is pumped to sprinklers along the peak of a house and allowed to trickle down a sloping roof. The rate of evaporation is greatly enhanced in such a system because a much larger surface area is exposed to the night air. Roof sprays rely on a little external power to get the water to the roof and hence do not qualify as completely passive systems. But the total amount of energy consumed for pumping is very minimal compared to the energy saved by the added cooling rate attained. Excess water can be captured and reused or used elsewhere on the site.
A passive evaporative system developed in California is shown in Fig. 31. An open pool of water located above the living spaces on the north side of a house is shaded from the summer sun but exposed to the cool north sky both day and night. Evaporation from the pool surface, aided by radiation and natural convection, keeps the water in this pool 30°F below the outside air temperature on a hot summer day, without the use of movable insulating panels. Natural convection brings this cool water into the house and draws heat back up to the pool as shown.
With all evaporative cooling methods, it is important to maximize airflow across the exposed water. Fresh air must be continually available to replace the humid air being built up near or over the water. Failing this, air will be quickly saturated with water vapor, and the evaporation and cooling rates will decline abruptly. Lips, edges and other structures or buildings that could block or deflect prevailing winds away from the water surfaces should be studiously avoided. Sometimes, a small fan to disturb the air over a pond will greatly aid the evaporation rate on a hot, sultry day or night.
Even with direct, active evaporative cooler systems, provision of interior thermal mass combined with direct evaporative cooling is a combination that works effectively. During the day, the structure can utilize the stored coolth in the walls and floors, and maintain an improved level of comfort while reducing power requirements of direct evaporative cooler system. In many areas of the southwest which are considered hot, arid zones, periods of higher humidity renders mechanical evaporative cooling unsatisfactory even when optimized techniques are used. A solution to this is the two-stage evaporative cooling system, which has been shown to be an effective alternative to direct evaporative cooling or refrigerated air-conditioning.
While not a passive system, two-stage evaporative cooling is an important element to be considered as part of passive cooling strategies. Cooling is accomplished by pre-cooling ambient air without humidification before further cooling by evaporation. The cool air entering the structure is then exhausted, typically through areas of heat gain such as windows or the attic. The pre-cooling may be accomplished by a combined cooling tower, heat exchanger unit, or by nocturnally cooled rock bed through which air is drawn. The second stage, evaporative cooling, is accomplished by a standard commercial evaporative cooling device, or by passive cooling elements of earth tubes or cool towers. Rock bed mechanical cooling has been used extensively in Australia with high degrees of effectiveness.
Two-stage evaporative system can also be combined with active and hybrid solar heating systems using the same storage (rock bed) system for both seasons. Working systems have been developed and demonstrated. This type of system is necessarily suited for new construction because of the requirement for the rock bed, which is most effectively located beneath the structure. It works well during hot, humid periods in the southwest using only slightly more power than direct evaporative cooling and the comfort attained is similar to that of refrigerated air-conditioning.
A typical system consisting of two evaporative coolers and a large rock bed is shown in Figure 31. At night, one evaporative cooler cools the rock bed while the other cools the house using a one-stage evaporative cooler. During the day, hot outside air is drawn through the night-cooled rock bed where it is pre-cooled before entering the main house evaporative cooler. Since no moisture has been deposited in the rock bed, the pre-cooled air has not had moisture introduced into the house. An attractive feature of this type of system is the combining of heating and cooling systems in order to make the best possible use of components during the entire year. An air heater may be used to provide hot air during the heating season to the rock bed where the rock bed, fans, ducts and many of the control systems are used both during the heating and cooling season.
Recuperative and regenerative evaporative cooling options are other methods to produce greater comfort using evaporative cooling. These techniques use the relatively cool air exhausted from the structure to improve the performance of the evaporative cooling device. Evaporatively cooled water reduces in temperature the ambient air in the heat exchanger without humidification as it enters the structure. The cool, dry air warms a few degrees as it passes through the structure and exits through the evaporative cooling device or a cooling structure. Since the exiting air is cool and dry, the wet bulb temperature is lower and the water produced by the evaporative cooling device is cooler than if ambient air were used. The rock bed heat exchanger and the evaporative cooling device could be combined into a single unit. If the rock bed is used to store heat in the winter, the cost effectiveness of the system is improved.
NOTE: The psychometric chart should be used at all times to analyze the effect of changing air conditions in these systems. As a rule of thumb, pre-cooling the air ten degrees will cause a three degree decrease in the output temperatures of an evaporative air cooler. The improper use of this rule can lead to errors of judgment when analyzing the results of changing conditions.
Because of the large volumes of air that are moved in an effective evaporative system, the ducts must be large and appropriately sized. Typically, evaporative cooler ducts are at least three times the cross-section area of ducts refrigeration; ducts should be laid out using the shortest route possible and a minimum of turns. Evaporative cooling has been shown to be an effective alternative to refrigerated air-conditioning throughout the desert regions of the southwest. The selection of the particular evaporative cooling techniques must be made carefully through analyzing the local climatic conditions. These cooling systems should be integrated into the design of the home and where possible, with the design of the solar heating system. By integrating these systems at the design stage, greater efficiencies and more attractive economics can be obtained.
http://www.azsolarcenter.com/technology/pas-3.html
Obrigado- quim.estrada
- 10 julho 2009
Eu estou a tentar implementar um esquema simples: colocar uma ventoinha para insuflar ar para dentro de casa, mas só consigo encontrar extractores. A ideia será, com recurso a um programador, ligar a ventoinha e insuflar ar durante a madrugada no Verão, e durante a tarde no Inverno.
Algúem sabe se existe o contrário de um extractor, para tubagem de 10cm?
Obrigado,
Joaquim- J.Fernandes
- 10 julho 2009
Quim,
No verão nem precisa de ventoinha, se tiver uma entrada de ar a baixa cota, 20 ou 30 cms do chão, numa fachada em que a parede não estivesse muito exposta à radiação solar durante o dia, Norte de preferência, e uma saída de ar junto ao tecto, vai provocar uma corrente de ar natural, que de noite faz entrar ar fresco e sair ar quente. Convém é durante o dia fechar a grelha de entrada.
No Inverno não ganha nada em meter ar do exterior para o interior, já que, em dias de Sol, este não ultrapassa os 15º, 16º. No Inverno ganha é com o efeito de estufa provocado pela radiação solar que incide nos vidros.
Quim,
No verão nem precisa de ventoinha, se tiver uma entrada de ar a baixa cota, 20 ou 30 cms do chão, numa fachada em que a parede não estivesse muito exposta à radiação solar durante o dia, Norte de preferência, e uma saída de ar junto ao tecto, vai provocar uma corrente de ar natural, que de noite faz entrar ar fresco e sair ar quente. Convém é durante o dia fechar a grelha de entrada.
No Inverno não ganha nada em meter ar do exterior para o interior, já que, em dias de Sol, este não ultrapassa os 15º, 16º. No Inverno ganha é com o efeito de estufa provocado pela radiação solar que incide nos vidros.
Daí que no Inverno, o uso das HRU faz sentido, como está mencionado nos posts anteriores.0.0208 seg. NEW
