Ventilation Cooling Effects of the Rammed Earth Wall

Ventilation Cooling Effects of the Rammed
Earth Wall Built in the Hotel Guest Room
A
B
C
Kumiko HATANAKA
Hiroki TOYOSAKI
Yuichiro KODAMA
[Gifu City Women's College]
[Yugo Architects]
[Kobe Design University]
D
Ryuichi ASHIZAWA
[University of Shiga Prefecture]
Email address of corresponding author: [email protected]
ABSTRACT
In Nov. 2013, a hotel was completed beside the Biwa-lake in Moriyama city, Shiga Prefecture,
Japan. This is a three storeyed building with 14 guest rooms. The main structure is reinforced concrete
but the rammed earth walls were built as the partitions between guest rooms. The rammed earth, which
was made from local and natural soil, was expected to work as a thermal mass for passive cooling in the
summer time. Each hotel guest rooms faces to the west and has a good view of the lake. In this area, the
prevailing wind in the summer time was west-east, and the ventilation cooling, utilizing this wind was
planned. The design of this building was studied based on the results of simulation studies and it was
expected to reduce 75% of cooling load. This paper discussed; 1) the design process of this building, 2)
the results of simulation studies, 3) the performance of the ventilation cooling effects.
1. INTRODUCTIONAND BACKGROUND
Building low environmental impact architecture, throughout the life cycle, is a form of construction
required for the coming years.When you build a building, making buildings that used local natural
resources of the land, as much as possible,is the new imperative. Production of soil wall is known for its
lesser environmental load or energy consumption than reinforced concrete. Rammed-earth,which is
made by pressing soil inside frames, has a beautiful layered texture and humidity conditioning, and large
thermal capacity. Then, we can use this wall, indoors, as a thermal mass to reduce heating and cooling
load. In the former investigation we made experimental building with rammed earth in Kobe, then
simulated and measured the thermal performance of the building. We presented how to use the rammed
earth as thermal mass in the area.
In Nov. 2013, a hotel was completed beside the Biwa-lake in Moriyama city, Shiga Prefecture,
Japan by Architects Ryuich Ashizawa Architect & Associates, and Soil-wall consultants, Kumiko
Hatanaka design office, as shown in Figure 1(a). This hotel has 3 rammed earth partition walls, as
shown in Figure 1(b). The authors investigated with the former method how many cooling load this
rammed earth reduced. Furthermore, for more effectiveness, the effect of passive cooling by outside air
intake was subjected to ventilation simulation in order to determine the opening position.
Author A is a M. Design and lecturer at Gifu City Women's College, Gifu, Japan. Author B is a M. Design and Architect at Yugo
Architects, Kyoto, Japan. Author C is a Dr. Eng. and Professor at Kobe Design University, Kobe, Japan. Author D is a Associate
Professor at University of Shiga Prefecture, Hikone, Japan
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a) The Hotel and Music hall
b) Guest room 4
Figure 1 a) West face of the hotel seen from the lake. A music hall is on the left side of the hotel, b) The
guestroom on the right wall is a rammed earth.
2. DESCRIPTION OF THE ARCHITECTURE
The hotel has three stories with fourteen guest rooms, one restaurant and one banquet room. The
hotel has a wide view to the lake in the west. The Music hall that is used mainly for wedding ceremony
is on the north to the hotel. The walls of the guest rooms are built with reinforced concrete except one.
The floors are made by raised wood. Rammed earth walls are used as partition for rooms.The room has a
rammed earth wall in the north or south. The windows are designed to ventilate from the west, the
lakeside to the east, as shown in Figure 2(a) & 2(b).
Rammed earth a) Main plan
b) Part plan
Figure 2
a) Music hall and 3rd floor plan and target room 4 for simulation, and b) Part plan of hotel
room, Room 4
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3. SIMULATION FOR THERMAL PERFORMANCE IN SUMMER (GUEST ROOM)
3-1. Simulation Model and Method
Although the forms of 14 guest rooms are varied, we computed the cooling load of “Room 4”,as
shown in Figure 2(b), in the summer as a typical room. The room is twenty two square meters wide. The
plan and elevation is distorted. The room is four metre wide on the west side. Although there is a
bathroom and a closet in the east, for the simulation we assumed it simple form regardless of the parts.
Figure 3(a) & 3(b) shows common details of the shape and specifications of room to simulate. We show
the result of simulation on next page. On these information shown below, we varied materials of thermal
mass.
The room was considered to be 4m wide, 4m deep, and 2.5m high. The opening of terrace side is
made with double glazing in wooden frame. The wall thickness of guest room is 250mm, so we
simulated considering that there are no heating affect by the next room which shares the wall as well as
upper or lower rooms. Therefore, other than the west face, a glass wool of 500 mm thick on the outside
of the Thermal mass was considered. We set 2.3m depth eave which is positioned over the terrace and
1.8m length on the sidewall of the terrace. As internal heat, we set 210J/h from refrigerator constantly,
and 882J/h from two hotel guests who stay between 17p.m. and 8a.m. in the guestroom. We assumed
that during the night time, between 18p.m. and 7a.m. a curtain would be closed as a night insulated door
and when the outdoor temperature is between 18- 26 ºC, the outdoor air inlet would be open. In this case,
simulation model is Room 4, which is call “Real model”. There is a rammed earth wall at north side wall.
The floor was covered with a wooden floorboard. The west side have big window. The walls of guest
rooms are built with reinforced concrete except one, as shown in Figure 3(a) & 3(b). The thermal mass
material is changed, and what kind of cooling load, was calculated according to the flow diagram, as
shown in Figure 4(a). Material constituting the respective models, are as shown in Figure 4(b). Material
properties are, as shown in Figure 4(c). We simulated the thermal performance with the design tool
“Solar Designer ver.6” developed by the authors.
a) The model used for simulation
Figure 3
b) The data used for simulation
a) Specifications of simulation model of “Real Model”, b) Data used for simulation
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a) Simulation flow
b) Materials of each models,
c) Thermal mass material properties
Figure 4
a) Simulation flow, b) Materials of each models, c) Thermal mass material properties
3-2. Thermal performance in summer
1.20
1.11
1.00
0.78
0.80
0.60
0.40
0.20
0.00
1.11
1.05
0.95
1.00
0.86
0.80
0.60
0.40
0.20
0.00
A
Real model
a) Model types A & Real model
Figure 5
Cooling load（GJ/year)
Cooling load（GJ/year)
1.20
A
B-1
B-2
B-3
b) Model types A & B
a) Annual cooling load for A & Real model, and b) Annual cooling load for A & B types
Figure 5(a) shows the comparison of the cooling load for “model A”, made in wood (plywood),as
shown in Figure 4(a), 4(b), 4(c), with the “Real model”, as shown in Figure 2(b). Rammed earth
thermal mass walls are expected to work well for the cooling load. B-1 has a rammed earth wall in the
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north side, and the rest of the walls of the guest room is built with wood, as shown in Figure 4(a), 4(b)
& 4(c). B-2 has 3 rammed earth walls. B-3 has 5 rammed earthwalls, as shown in Figure 4(a), 4(b) &
4(c). The analysis shows that the cooling load decreases with increase in rammed earth walls, as shown
in Figure 5(b). Figure 6(a) shows thermal mass works well for the cooling load. C-1 has one reinforced
concrete wall in north side and the other walls are built with wood, C-2 has 3 RC walls, C-3 has 5 RC
walls, as shown in Figure 4(a), 4(b) & 4(c). In this case also, the cooling load decreases as the amount
of RC walls increase, as shown in Figure 6(a). Figure 6(a) shows comparison of cooling load for “Real
model”, which has wooden floor and one rammed earth wall. So, it has less thermal mass and a little
bigger cooling load than C-3. But “Real Model” has less cooling load than C-2.
1.20
1.00
0.99
0.84
0.80
0.70
0.78
0.60
0.40
0.20
0.00
Cooling load（GJ/year)
Cooling load（GJ/year)
1.20
1.00
0.91
0.95
1.01
0.80
0.60
0.40
0.20
0.00
C-1
C-2
C-3
Real
model
B-2-1
(B-2)B-2-2
B-2-3
a) Model C-types & Real model b) Model B-types comparison and material properties
Figure 6
a) Annual cooling load for C types & Real model, b) Annual cooling load for B types and
Thermal conductivity and specific heat capacity of rammed earth with various density.
Figure 7
Annual cooling load / Ventilation mode and no ventilation mode
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Rammed earth has various conditions determined by what the type of soil used, and how hard the
earth was rammed. So,we considered three different thermal conductivity and volumetric specific heat
of rammed earth: Rammed earth 1 is high density; Rammed earth 2 is mid density; Rammed earth 3 is
rough, low density. Figure 6(b) shows that as the density of the rammed earth increases, the cooling
load is lower. The cooling load comparison of the cases shows that in the dense version built, the
cooling load is reduced. In case of the “Real model” the cooling load decrease, if we compare to C-1 &
C-2 modes. When only active cooling is used windows are closed and air change rate of 0.5 times per
hour is considered, and when the outdoor temperature range is 18~26ºC, 15 ACH, natural ventilation is
used. The simulation results of 3 ways using,ventilation mode and non-ventilation mode, and cooling
load is reduced by 75% in ventilation mode, as shown in Figure 7.
3-3. Conclusion This examination shows ventilation is effective to be used in the guest room to reduce the cooling
load. And Rammed earth is an effective material to reduce cooling load and embodied energy. Then,
rammed earth is the next generation’s material. And,the simulation is an effective tool for verification of
the same.
4. DESIGN OF THE WINDOW (GUEST ROOM)
4-1 Simulation Model and Method
The thermal environment simulation, showed cooling load reduction and the ventilation cooling
effects obtained by taking advantage of the heat storage of the rammed-earth wall. Night ventilation takes in the cold air of the night, and stores it until the next day. For this purpose, it is necessary to
ventilate an appropriate amount while considering appropriate security and privacy. In this section, we
describe the design of the opening to ensure a desired flow distribution and airflow, and introduce the
simulation results of the flow.
Western windward side is a picture window to capture the views of Lake Biwa. In order to retain
the view, a window for ventilation was provided for at the position of the feet.The louver door installed
at the east entrance leeward location was designed to allow wind flow, and through the common corridor,
as shown in Figure 8(a) & 8(b).Under these conditions, we investigated the air volume flow and felt the
wind present at the guest locations. We simulated the wind flow with “STREAM”.
4-2 Study of the wind flow
Study of the relative positions of the inlet and the outlet are, as shown in Figure 8(a) & 8(b). In
Model 1, a window is arranged at a position frontally facing the entrance, and in Model 2, the window is
arranged in a position diagonal to the entrance, as shown in Figure 8(a) & 8(b). In view of the locations
of residents and placement of furniture, we decided to model-1 wind flow in a region where there is a
bench in front of the bed, as shown in Figure 8(a) & 8(b).
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Figure 8
(a) Window layout for Model-1
Figure 8
(b) Window layout for Model-2
4-3 Study of the amount of air
In order to easily adjust the air flow, the position and size of the opening of the common corridor
was changed, as shown in Figure 9. Model 3, as shown in Figure 9, is a view after the change.
Originally, a window was placed near the ceiling of the front of the entrance door that had been placed
randomly, and took larger opening area. As a result of the reconfigured scheme, the wind went from the
foot opening, and goes out of the high window, and air volume is increased than Model 1.
Figure 9
Windows layout for Model-3
4-4 Conclusion
In order to enable the guest to adjust and incorporate their own style, the authors consider how to
open the window and placement of the opening, and were able to ensure proper ventilation and air-flow
path.
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5. CONCLUSION
The building design, based on the above studies, was completed and is currently in operation. The
authors consider making comparison between the actual measured value and actual simulations,
responsive user praxis of opening the window to introduce outside air, and the feel and experience of
hotel guests through questionaire, and the mechanisms of outside air intake. Furthermore, our objective
is to advise the hotel management on the low energy practices.
6. REFERENCES
Japan Meteorological Agency, AMeDAS (Automated Meteorological Data Acquisition System)
Weather Data, 2012.
Hatanaka, K.Ashizawa, R. Kodama, Y. Igaki, R. 2012 Thermal performance of the hotel guestroom with
rammed eartn wall-Case Study of thermal mass effect on cooling load reduction. Summaries of
technical papers of annual meeting Architectural Institute of Japan. September 2012.Nagoya:519520.
Miyaoka, F. Kodama, Y. Hasui, C. Hatanaka, K. Takemasa, K. 2007. Application of Thermal
Performance of Rammed Earth Wall on Passive Design: A Case Study in Temperate Climate of
Japan, Proceedings of the 24th International Conference on Passive and Low Energy Architecture
(PLEA), Singapore, November 2007:468-475
Kodama, Y. Miyaoka, F.Hasui, C. Hatanaka,K. Takemasa, K. 2008. Application of Thermal
Performance of Rammed Earth Wall on Passive Design : A Case Study in Temperate Climate of
Japan, The Bulletin of Kobe Design University, 2008.http://kiyou.kobe-du.ac.jp/07/thesis/0301.html
Ashizawa, R. SETRE Marina Biwa-lake, Shinkenchiku(New Architecture), Japan. January 2014:150157,196.
Ashizawa, R. Hatanaka, K. Toyosaki, H. et al. SETRE Marina Biwa-lake, The Kenchiku Gijutsu Japan.
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Toyosaki, H. Kodama, Y. Kuchii, Y. 2007. Environmental Responsive Housing:A Multi Family
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Toyosaki, H. 2007. A study of the space composition method of housing and the effect of cross
ventilation.Summaries of technical papers of Annual Meeting Architectural Institute of
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CFD tool STREAM.http://www.cradle-cfd.com
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