11 th NTERNA T10NAL BRCK/BLOCK MASONRY CONFERENCE TONGJ UNVERSTY, SHANGHA, CHNA, 14-16 OCTOBER 1997 LOW ENERGY ONE FAML Y MASONRY HOUSE Tor-Ulf Weck l 1. ABSTRACT The paper describes the principies of design and building of an one family house built in masonry where special emphasis was taken to decrease the energy consumption and especially the use of such energy that has to be bought from externai energy producers. n Finland there is arranged every second year a housing fair where different housing producers present their latest innovations and products. Masonry industry has taken part in these fair every time. n summer 1996 a specia1 effort was made to build an ordinary one family house in such a way that the energy consumption is low, but the housing comfort is the same as in all modem houses. One further requirement was that the house should not be considerably more expensive than an ordinary masonry house. This is also due to the fact that all the houses on the fair are sold to private persons after the fair. An ambitious goal was set for the low-energy brick house built for the Ylõjãrvi housing exhibition: the heating bill had to be only one fifth of that for a conventional dweling of the same size. The design did neither incude any non tested new materiais nor did it require special skills from the workers. The mass of the masonry structure enabled use of passive solar energy, convenient fire places both for heating and as a complement to an electric stove. Ground energy was also used as an addendum to other energy sources. The final energy consumption in the Finnish cold cimate is only 65 kwh/m 2 which is less than a third of an average energy consumption for a traditional one family house. f solar panels and ground energy are used, the need for externai energy decreases to 20... 25 kwh/m 2. Keywords: Masonry; Housing; Energy conservation. Professor, Department of Architecture, Helsinki University oftechnology, P.O.BOX 1300, FN - 02150 HUT, Finland. 790
2. NTRODUCTON n Finland there is every year arranged a housing exhibitian, in which producers of building material, structures and HV AC-installations are presenting their latest products. The area consists usually of 30 to 50 one-family houses, row-houses and apartments. After the exhibition the houses and apartments are sold and used for normal iving. n year 1996 the exhibition was hed in Ylojiirvi some 200 kilometres north from the capital Helsinki as shown in figure 1. n Ylojiirvi the average temperature in January is -14 C and in July + 14 C. This means that the winter is rather cold, but during on a sunny day in summer the temperat\,re inside a building can rise to uncomfortable leve. YlOjarvi 3. THE AMS OF THE ARCHTECTURAL DE SGN During the last years there have been built in Finland several low-energy houses, which have ali been of light weight structure. Aims have been good thermal insulation, controled airtightness of structures and a Fig 1 Location of the lowenergy house ventilation system equipped with heat recovery. Here there was added one important new feature, the heavy structural material brick. With the mass of the structure the building can absorb and store the free energy provided by the sun, which even in such a northem country as Finland provides an important source of energy. This low-energy house is an example how energy saving, exploitation of free energy and comfortable iving can be combined. Ali materiais, structural solutions and technologies have been used earlier and proved to be good solutions, thus providing a secure base for a good building. The key to success has been to take the right portion of each component and to add them in a way that suits the Finnish cimate. Modem technologies combined with traditional building material have given this result. 4. THE PLAN OF THE HOUSE Planning of the house started from the format of the house. The most energy efficient form for a structure is aboli, but as this is structurally difficult to build, the starting point was chosen to be a cube. Most of the openings were oriented towards the south with a winter garden on that side. From the northem side the upper comer was cut off to eliminate the area of wal and roof towards the northem outdoor space. This also enabled the sloping roof. The result can be seen from the facade view in figure 2. 791
Figure 2 Facade to north-west Even on the southem side the roof is slightly sloping, giving better,positioning for the solar collectors on the roof, see figure 3. The comer was cut here, too máking better possibilities for a winter garden heated by the solar power. Figure 3 Facade to south-east The interior design was govemed from the wish to use only high quality materiais and rooms with lots of space. n the ground levei there are living room and a room with traditional Finnish open fire place as well as kitchen and dining room. A Finnish "sauna" with dressing room and place for laundry is in the basement, too. Bedrooms are in the upper floor with doors to an aula so that there is no need to pass through any rooms. The plans are shown in figures 4 and 5. 792
;. - -c ->- - GARAGE SHED FREWOOD Figure 4 The fitst floor plan :, ;,, r-- _ o. - - J, r - J Figure 5 The second floor plan 793
5. BUll.DNG STRUCTURE The building structure is basically made of load bearing masonry walls. Outer walls are cavity walls, the inner leaf 130 mm thick and outer leaf 85 mm thick with mineral wool 150 mm as a thermal insulation layer. nner walls are mainly made of 130 mm thick masonry. On the southem side behind the winter garden a transparent insulation material is used with a backing wall made of thick masonry. n this way all the solar energy can penetrate the insulation layer and be absorbed into the inner masonry wall. Windows are made with a special select1ve coated glasses with a k-value 1,0 W/m 2 when the average triple glazed windows in Finland have a k-value 1,8 W/m 2. The entrance doors are naturally well insulated, too., 6. ENERGY CONSERVATON ASPECTS Above has already been mentioned several structural aspects that contribute to energy saving. The saving is based on minimizing heat losses and exploiting free energies. Brick walls are effectively utilized in the building as heat-storing structures. Especially in the spring and autumn, when variations in the outside air temperature are large, the energy stored in the building's masonry structure can be used for nighttime heating. Naturally, this reduces the daily need for heating energy. The building's above-average insulation and thermally efficient windows as well as the controlled airtightness of the structures have been designed not only to reduce energy consumption but also to provide good air quality. The ventilation system is mechanical and features efficient heat recovery. When the wood-buming fireplaces, baking oven and cooking range are in use, the indoor air pressure can be changed so as to ensure an adequate supply of air for combustion. 7. HEATNG SYSTEMS The energy needed to heat the building is produced by a ground heat pump and solar energy collectors. The eight square metres of solar collectors store the heat in two separate water storage tanks. The solar collectors produce enough energy to heat the house and its hot water for 5-6 months of the year. Solar energy is also utilized by the massive brick walls, which are extemaly clad with transparent insulation material as mentioned earlier. 'fhe south-facing winter garden also plays a part in radiating solar energy into the building. The ground heat pump is used to heat the water storage tanks during the winter months. The pump brings ground heat into the building from a depth of '150 metres. The system has separate water storage tanks for heating and for hot water. Energy is saved because the temperature of the heating water can be kept down to the minimum leve required. 794
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8. CALCULATED ENERGY SAVNGS Technical Research Centre of Finland (VT) has estimated the thermal requirements of the low-energy house. ts annual heating energy consumption was calculated at 65 kwh/m 2, which is about a half of the consumption of a conventional house of the same size. With energy being produced by both solar collectors and the ground heat pump, the annual consumption of purchased energy was estimated at 20-25 kwhlm 2. The energy SOLAR HEAT------. 16% SOLAR vvl.l.::v THERMAL NSULATON WALL 2% HEAT PUMP 22% 5% OCCUPANTS AND EQUPMENT 13% Figure 7 42% Sources of heat resources performance of the wall clad with transparent insulation material is naturally dependent on the amount of solar radiation that it receives. During the winter the energy gain from the externai wall is 200-400 kwh per month. The calculated!jeat resource percentages are shown in figure 7 and the heat consumption percentages in-figure 8. From figure 7 one can observe that the ground heat is the major source of energy, but solar energy despite Finland's northern position stands for 23 % of ali heating energy. Figure 8 in turn reveals that ventilation in this well insulated building is responsible for half of the heat losses while the mantel of the building consumes the other half. 796
ROOF- - 8% DOORS WNDOWS 17 % EXTERNAL VV,",LL"'----... 19 % FLOOR 6% Figure 8 VENTLATON 49% Sources of heat losses.9. CONCLUSONS The project shows as it also was the meaning, that with modem proven technology, the externai heating energy for an one family house can be reduced up to one third of that for an average house in Finland. This requires simultaneous use of both solar and ground energy together with well planned ventilation with heat recovery. This ali increases the building costs, but the money is saved bach withing the life-time of the building. Thus this way of building is national economically to be recommended. The final results can naturally be obtained first after several years of use when accurate knowledge of maintenance costs are known. t is also possible to use only some of the energy saving procedures for example good architectural building planning taking well into account the energy saving aspects. n this way an optimal solution can be found where the extra building costs are minimized while at the same time the need for externai energy is low. The results cannot directly be transferred in other are as with different c1imatic conditions or building environment. The Finnish example could however functions as an innovative example of what possibilities there lies in masonry structure as an energy saving structural material. The house was built by the Finnish Brick ndustrial Association with financia assistance from the the Ministry of Trade and ndustry and the Technology Development Centre (TEKES). Construction work on the low-energy brick house began at the YlOjãrvi housing exhibition site on 1st April 1996. The building was completed on 30th June 1996. 797