Review of the Passive Solar Township Health Center Pilot Project

34151 Review of the Passive Solar Township Health Center Pilot Project March 22, 2002 Asia Alternative Energy Program (ASTAE) The World Bank, 1818 H Street N.W., Washington, D.C. 20433 USA  Review of the Passive Solar Township Health Center Pilot Project1 Introduction Township Health Centers (THCs) in China provide basic health services for nearly 80% of the rural population. The functions of THCs are primary care and referral, maternal and child health, first aid, common disease diagnosis and treatment, disease prevention and information collection, as well as supervision of village health workers. However, in the poor rural areas, poor conditions in the THCs, such as dirt, poor indoor air quality and obsolete equipment, have severely affected their service function. To improve the quality of health service delivery to the rural poor, the Government of China is implementing the Health VIII project in 71 counties in seven provinces (Qinghai, Gansu, Shanxi, Henan, Anhui, Guizho u, Chongqing). With assistance from the World Bank, the Health VIII project seeks to improve rural health resource planning, establish health information systems and improve basic health services and disease intervention. Toward these ends, the project is building or rehabilitating 1102 Township Health Centers (of which, 104 are in Qinghai; 199 in Gansu; and 136 in Shanxi). The new buildings have to meet the basic requirements stipulated in Health VIII “Criteria for Township Health Center Construction” such as: being properly spaced, properly functioned, properly equipped, and satisfying the requirements of safety and sanitation. Many of the first THCs built under the Health VIII project have experienced severe heating problems, particularly those in the 3 coldest provinces of Qinghai, Gansu and Shanxi, where heating is required for over 6 months of the year. Coal is not locally available and transportation is difficult in most remote communities. In addition, the coal is expensive, which increases operating costs and limits service when coal supplies are low. As a result of coal supply problems, the THCs are often too cold to provide adequate health services in winter. Another issue is the indoor air quality of the THCs as a result of burning coal in poor coal stoves. The typical THC has a coal stove in each room for cooking and heating. The stoves are poorly vented and the threat of carbon monoxide and increased particulate levels makes the indoor environment unsafe, qualifying many of the THCs as “Sick Buildings.” A high fluoride content in the coal of some counties only adds to the indoor air pollution problem. Using grant funds and technical assistance mobilized by the Asia Alternative Energy Program, the Ministry of Health included passive solar design elements in three of the clinics to be built under the Health VIII project. These prototype clinics were constructed in 1999 in Huzhu county (Qinghai province), Tanchang county (Gansu province) and Tianzhen county (Shanxi province). They were designed to show the extent to which heating coal could be cost-effectively reduced and indoor environments improved by using passive solar and energy efficient design elements. The prototype THCs are now in 1 This report was prepared by John W. Spears, Sustainable Design Group Inc., 22923 Wildcat Rd., Gaithersburg, Maryland, 20882 USA. use and have achieved good results in reducing coal use, saving energy, improving comfort and indoor air quality and protecting the environment. During this prototype phase, three design institutes, local solar experts and consultants were trained in energy efficiency and passive solar design. The prototypes provided valuable hands-on experience for the design institutes, builders, and local officials. Each prototype received widespread publicity and was well received by county and local officials. The prototype THCs were instrumented for energy, comfort and indoor air quality and data was collected from April 2000 through April 2001. This report evaluates the experience at each of the prototype clinics based on instrument data and discussions with THC staff. The lessons learned during this pilot phase, and specified in this report, are being incorporated in a follow- up demonstration project in which about 30 pilot demonstration passive solar clinics will be built in the same three provinces. Summary results of monitoring & evaluation The three prototype passive solar THCs were monitored for indoor temperature, indoor air quality, passive solar system performance and energy consumption from April 2000 through April 2001. Each passive solar clinic was paired with a traditional (unimproved) clinic and a new non-solar clinic that were also monitored as a control group. The measurement of indoor temperature, indoor air quality, passive solar system performance and weather conditions was done with data recorders that were read monthly. Energy use data was collected from utility bills and fuel purchase records. The prototype passive solar THCs performed well and demonstrated better indoor comfort, indoor air quality and lower coal consumption than control group clinics. Winter indoor temperatures in the passive solar THCs are typically considered comfortable during sunny days without the need for a fire in the coal stove. The non-solar THCs usually burn coal all day during the heating season to maintain comfort. Solar and control clinics were also fitted with carbon monoxide sensors to measure indoor CO levels. The non-solar THCs that had indoor coal stoves commonly had numerous incidents of high CO, which was directly related to the coal stove use. In many cases the CO levels were dangerously high for prolonged periods. None of the passive solar THCs had any CO detected because they had no coal stoves. The passive solar THCs used no coal for heating compared to the non-solar THCs that used 5 to 34 tons of coal for heating over the heating season. While the performance data for the passive solar THCs is encouraging, the experience reviewed in this evaluation indicate that there are areas where performance can be significantly improved during the next phase of the project. Areas for improvement are: 1. better insulation details to assure thermal integrity; 2. higher insulation levels; 3. more attention to quality control during construction; 4. simplified designs; and 5. improved training in passive solar building operations and maintenance. 2 The 3 prototype designs provided valuable hands-on design experience for the concerned design institutes, revealed implementation constraints and offered some valuable design and construction lessons that will be applied in the next phase. The primary issues that were identified and will be addressed are: 1. Consultation with users and occupants during design development. 2. Space allocation and functionality – appropriate space design reduces heating needs. 3. Quality control during construction. 4. Complexity of the designs. Simple designs always work better. 5. Overhang design. Overhangs should be reduced in the colder climates. 6. Suitability of materials. Some materials used in the prototypes are not suited for direct solar exposure and high heat. 7. Better insulation details and higher insulation levels. 8. Occupant training. Occupants need to be trained in how to operate the building for maximum performance. This process needs to start at design stage, some design options might be ruled out on the basis of user response or preference. 3 Results Details of the pilot project monitoring and evaluation are presented in this section. Three clinics were monitored in each province, an older un-renovated clinic and a newer clinic that form a control group and the passive solar clinic. Gansu 3 – Guan E Township Hospital The Guan E Township Hospital is an older building with a center entrance and 6 rooms that open to the outside. It is a small clinic with a floor space of 115 m2 . The building is constructed of solid brick with no insulation and small single pane windows. There is no interior hall. Therefore, one must go outside to change rooms. Some of the rooms have small coal stoves that are used for cooking and heating. The building is oriented with an east-west ridge, which allows for a good southern exposure. Gansu 3, Old THC 40 30 20 Degrees C 10 0 -10 -20 Aug-00 Sep-00 Oct-00 Nov-00 Dec-00 Jan-01 Feb-01 Mar-01 Apr-01 Outside Air Zone 1 Zone 2 Zone 3 Zone 4 Figure 1 Monitoring Data for Guan E Township Hospital, Gansu Province Figure 1 shows the outside temperature and temperatures in 4 rooms over the 2000-2001 heating season. Two rooms had coal stoves (Zone 1 and Zone 4) and the other two rooms were unheated. In the winter, the unheated rooms averaged from 5 degrees C to –2 degrees C. The heated rooms averaged 10 to 18 degrees C with the higher temperatures only occurring briefly. The coal usage caused the Carbon Monoxide alarm to go off repeatedly. The CO alarm reportedly went off an average of 11 times per day. This is a clear indicator of unhealthy and even dangerous Carbon Monoxide levels in the health care clinic as a result of burning coal. Approximately 5 tons of coal was used over the 4- ½ month heating season. At US$48 per ton, the clinic spent US$240 on coal for heating, boiling water and cooking. This amounts to roughly 10 kg coal per square meter of floor space per month (or nearly 50¢/m2 /month) during the heating season. 4 Gansu 2 – Ha Da Pu Township Hospital The Ha Da Pu Township Hospital is a relatively new building and the largest in the study. It is two stories tall and has 26 rooms with 460 m2 of floor space. The building faces east and west with the entrance on the north and no windows to the south. The single pane windows are tinted blue. The building is heated with a large coal central boiler located outside in a separate building. There are no thermostats or controls on the heating system. The system is manually stoked with coal and runs all winter. The building used 34 tons of coal over the 5-½ month heating season, which cost US$1,632 at US$ 48/ton. This amounts to roughly 13.5 kg/m2 /month or 65¢/m2 /month for heating coal. Gansu 2 New THC 40 30 20 Degrees C 10 0 -10 -20 Aug-00 Sep-00 Oct-00 Nov-00 Dec-00 Jan-01 Feb-01 Mar-01 Outside air Zone 1 Zone 2 Zone4 Figure 2 Monitoring Data for Ha Da Pu Township Hospital, Gansu Province With the boiler operating at full output through the winter, the indoor temperatures were still very cold. Figure 2 shows the indoor and outdoor temperatures from early July to early March. During the coldest days (-10 to -15 deg C), the average indoor temperature was between 5 and 12 degrees C. These are very cold temperatures for a hospital. The Carbon Monoxide alarm did not go off during the heating season because no coal was used in the building – the boiler is located in a separate building. 5 Gansu Solar – Nan He Township Hospital The Nan He Township Hospital is a 245.33 m2 passive solar design. The building incorporates both direct gain and vented mass wall techniques. The windows are primarily on the south wall with no windows on the east and west and only a few windows on the north for ventilation. The windows are a combination of double windows and site built double pane windows. The north windows have folding wood and 30mm polystyrene insulating shutters. The building is insulated with 150mm polystyrene foam insulation sandwich between a 240mm exterior brick wall and a 120 mm interior brick wall. The roof is insulated with 200mm polystyrene foam insulation. The indoor temperatures at the Nan He Township hospital, as seen in Figure 3, were in the same range as Gansu 2 above. Gansu 2 has a central boiler heating system and used 34 tons of coal to heat it. Gansu Solar has no auxiliary heating system and used no coal. Using a mid-range heating coal estimate of 11.5 kg/m2 /mo from Gansu 3 and Gansu 2, the passive solar design saved more than 15 tons of coal that would have cost nearly US$ 750 over the 5-½ month heating season. Gansu Solar 40 30 20 Degrees C 10 0 -10 -20 Aug-00 Sep-00 Oct-00 Nov-00 Dec-00 Jan-01 Feb-01 Mar-01 Outside Air Zone 1 Zone 2 Zone 3 Zone 4 Figure 3 Monitoring Data for Nan He Passive Solar Township Hospital, Gansu Province The passive solar design for the hospital at Nan He was found to have two major flaws. The first is that the solar overhangs were too long. Passive solar structures often have overhangs above the solar gain windows that shade the windows in the summer when the sun is high, but do not shade the windows when the sun is low in the winter. The south 6 wall overhang on the Nan He hospital was found to be fully shading the solar windows in April when the building could still use the solar heat. The second, and more serious, flaw is that there are many thermal bypasses in the structure. Insulation details show that there are many gaps in the insulation where heat has a path to flow through the concrete structure and steel reinforcement web between the insulation boards. The annex contains several examples of thermal bypass from the design details. These thermal bypasses significantly reduce the effectiveness of the insulation. Gansu Solar Mass Wall January, 2001 70 60 50 40 Degrees C 30 20 10 0 -10 -20 1-Jan 6-Jan 11-Jan 16-Jan 21-Jan 27-Jan Outside Air Outer wall Middle wall Inside wall Zone 4 Figure 4 Monitoring Data for Solar Elements at Nan He, January 2001 The mass wall temperatures, outside air and indoor air temperatures in January 2001 are shown in Figure 4. Sensors were placed in the wall in 4 places: 1 in the outer part of the wall, 2 in the middle of the wall and 1 near the inside surface of the wall. The outer wall shows good heating during the day when the sun is shinning. Cloudy days can be seen as lower temperatures on the outer wall (January 7,8,18, and 22-24). On sunny days the mass wall fluctuated from a low at night of 40 deg C to a high of 62 deg C with the outside air temperature fluctuating from -10 deg C to 8 deg C. This clearly demonstrates the potential solar heating benefit. The middle and inside temperatures of the mass wall however, follow the room temperature very closely. There is a 40 to 50 deg C difference between the inner wall temperature and the outer wall temperature. This is due to the high degree of heat loss from the thermal bypasses summarized above. Most of the heat collected by the solar air heater is lost to the outside through the uninsulated parts of the structure before it gets 7 into the building. In a well- insulated system, we should only see a 10 to 15 deg C difference between the inside and outside faces of the wall. This is an area of potential significant improvement in the performance of future passive solar systems. Conclusions for Gansu Solar The passive solar design of the Nan He Township hospital is basically sound. With some improvement in the details, this building could perform very well. The building has some significant thermal flaws that prevent it from operating at full potential. They include: 1. thermal bypasses in the concrete structure; 2. excessive overhang shading the windows late in the heating season; and 3. poor weather-stripping around doors and windows. There is also a problem with the way the building is operated. It is not unusual for the doctors to leave the front door open in the winter and to leave windows open. In spite of the problems, the passive solar building performed as well as the Gansu 2 building that had a central boiler. The Solar building however used no coal, cost nothing to heat and had no Carbon Monoxide pollution. Significant improvements in solar performance can be achieved with more attention to thermal details both in the structural design and in construction and more attention to good operation practices. 8 Shanxi 3 – Nan He Pu Township Hospital The Nan He Pu Township Hospital is a traditional 300 m2 design with 11 rooms arranged in one row. All rooms have a good southern exposure. There is a generous overhang to prevent summer overheating. The structure is all brick with a suspended ceiling. There is no wall or ceiling insulation. The windows are single pane. Most rooms have a traditional coal stove that is used for heating, cooking and boiling water and is vented through the wall with a pipe. Coal stoves vented in this manner cause severe indoor air quality problems and the Carbon Monoxide level in these rooms is often dangerously high. Shanxi 3 40 30 20 Degrees C 10 0 -10 -20 Aug-00 Sep-00 Oct-00 Nov-00 Dec-00 Jan-01 Feb-01 Mar-01 Apr-01 Zone 1 Zone 3 Zone 4 Figure 5 Monitoring Data for Nan He Pu Township Hospital, Shanxi Province Figure 5 shows the indoor temperatures in 3 of the rooms throughout the heating season. As you can see, the rooms were below freezing most of January and February. This is in spite of the fact that they had coal stoves in most of the rooms. Outdoor temperatures and coal consumption were not reported for the Nan He Pu Township hospital. 9 Shanxi 2 – San Shi Li Pu Township Hospital The San Shi Li Pu Township Hospital is an older building with 6 rooms, an entry area and a corridor linking all the rooms covering 160 m2 of floor space. The building is solid brick with small single pane windows and no insulation. Each room is equipped with a small coal stove used for cooking, heat and boiling water. Most of the coal stoves and their flues that vent through the wall were in poor condition\ leading to dangerously high Carbon Monoxide levels. Shanxi 2 40 30 20 Degrees C 10 0 -10 -20 Aug-00 Sep-00 Oct-00 Nov-00 Dec-00 Jan-01 Feb-01 Mar-01 Apr-01 May-01 Zone 2 Zone 3 Zone 4 Figure 6 Monitoring Data for San Shi Li Pu Township Hospital, Shanxi Province Indoor temperatures, shown in Figure 6, fell well below freezing from late November through late February. Zone 4 had a coal stove to keep the room warm. The combination of freezing indoor temperatures and Carbon Monoxide from the coal stoves makes for a very unhealthy environment. No data were reported on coal consumption or outdoor temperatures. 10 Shanxi Solar – San Shi Li Pu Township Passive Solar Hospital The San Shi Li Pu Township Hospital is a new 280 m2 passive solar building with 11 rooms built next to the old township hospital. The passive solar design incorporates direct gain windows and solar air heating panels. The building has all it’s windows facing south. The lower level windows are manufactured vinyl framed doub le pane windows. Windows on the upper level are double pane and built on the site. The outer wall of the building is 240 mm brick that encases a 60mm layer of foam insulation between it and a 120 mm brick inside wall. Sixty mm of foam insulation (R1.2) is too little insulation for this cold climate. Minimum insulation should be 100 mm to 150 mm (R3.5 to R5.3). The design also included electric radiant ceiling heating panels in some of the rooms, but the monitoring data indicates they were not used during the 2000-2001 heating season. Figure 7 shows that this passive solar building did not perform well in the more extreme environment of rural Shanxi. Room temperatures fell below freezing at night from December through February when outdoor lows approached –20 deg C. Generally, daytime room temperatures were bracing: between 0 deg C and 10 deg C all winter. No auxiliary heat was used all winter. Because coal use in the control clinics was not reported, it is not possible to assess the coal saved by this passive solar building. Shanxi Solar 40 30 20 Degrees C 10 0 -10 -20 Aug-00 Sep-00 Oct-00 Nov-00 Dec-00 Jan-01 Feb-01 Mar-01 Apr-01 May-01 Outside Zone1Hall Zone 2 Zone 3 Zone 4 Figure 7 Monitoring Data for San Shi Li Pu Township Passive Solar Hospital, Shanxi Province 11 A closer inspection of indoor room temperature, air temperature leaving the solar air panel and the outside air in December is displayed in Figure 8. The outside was very cold with lows from –15 to –20 deg C. The indoor room temperature was over 20 deg. C higher than outside however it still only averaged about 5 deg C. The solar air heater delivered 30 deg C air at noon on a good sunny day and you can see a direct rise in room temperature as a result. As the sun goes down however, the room cools off rapidly. This indicates that the room has a very high heat loss rate. This is caused by a combination of inadequate insulation levels, thermal bypasses and air leakage. Shanxi Solar Air Panel December, 2000 40 30 20 Degrees C 10 0 -10 -20 -30 8-Dec 11-Dec 14-Dec 17-Dec 20-Dec 23-Dec 26-Dec Outside Solar air panel out Zone 4 Figure 8 Monitoring Data for Solar Elements at San Shi Li Pu, December 2000 While the San Shi Li Pu Township passive solar hospital has a basically sound passive solar design, performance suffered from several technical problems arising from inappropriate materials, incomplete insulation coverage and poor construction quality. Namely, the solar air panels used polystyrene foam board painted black. Polystyrene will break down very rapidly when exposed to heat and sun. A proper design would use a foam insulator that can withstand the heat with a metal absorber plate painted black. One of the solar air panels did have metal absorber plates, but as installed, they did not fully cover the foam. The solar air panel used double- glazed glass built on site. When inspected, the weather stripping was found to be poorly installed and some of the glass was missing. Site built double-glazing is very difficult to do well in the field and is not recommended. At least one of the vent flaps that allows heated air to flow from the solar air panel into the room and cold air from the room to enter the panel was installed backwards. Several paths for heat conduction through gaps in the insulation (thermal bypasses) were built into the solar air heating panel, dramatically reducing its efficiency. These issues are presented with illustrations in the annex. 12 Conclusions for Shanxi Solar The building is basically a good passive solar design, however the following problems prevented it from performing well: 1. Inadequate insulation levels. Insulation should be increased from R1.2 to R3.5 or R5.3. At the current level, the heat loss is greater than the solar energy input. By reducing the heat loss, the passive solar system will keep the building much warmer. 2. Thermal bypasses increased the heat loss and deteriorated the solar air panel performance. Careful attention to insulation details is critical to good solar performance. 3. Site built double-glazing for windows and solar air heating panels is not recommended because it is very difficult to accomplish well in the field. 4. The foam insulation in the solar air panel will not hold up to the sun and temperature and needs to be replaced. 13 Qinghai 2 – Bain Tan Township Hospital The Bain Tan Township Hospital is a new building configured in a L shape over approximately 200 m2 of floor space (no detailed floor plan was available) with 8 rooms connected by a hall on the south and east side. The building is solid brick with no insulation. Each window opening contains two sets of steel- framed windows. This is a good alternative to more expensive vinyl double glazed windows and performs much better than site built double-glazing. Rooms were heated with individual coal stoves. Qinghai 2 40 30 20 Degrees C 10 0 -10 -20 Apr-00 May-00 Jun-00 Jul-00 Aug-00 Sep-00 Oct-00 Outside zone 1 zone 2 zone3 zone4 Figure 9 Monitoring Data for Bai Tan Township Hospital, Qinghai Province Figure 9 shows the monitoring data that was made available for the Bain Tan Township hospital. Unfortunately, winter data were not available at the time of this report. However, the data for the fall shows coal stove use in zone 1 and similar performance to the other older hospitals in the study. The building used 18 tons of coal over the six- month heating season. At US$ 63 per ton, it cost US$ 1,134 to heat the building . This amounts to roughly 15 kg/m2 /month or 95¢/m2 /month for coal. Hospital staff reported the Carbon Monoxide alarm went off constantly (40 times per day) in the winter and 2 times per day in the summer when they used the coal stove for cooking. This presents a very dangerous indoor air quality problem. 14 Qinghai 3 – Ba Zha Township Hospital The Ba Zha Township Hospital is a small traditional building design covering 100 m2 with 5 rooms connected by a hall on the south wall. This building is a classic passive solar sunspace design, a very appropriate design for this region. Each room has windows facing the south hall that acts like a sunspace. The sunspace collects solar heat, which warms the rooms during the day. At night, the doors to the rooms are closed to keep in the heat and the sunspace is allowed to cool down. With good insulation details, this design could be a model for passive solar buildings in this region. Double steel framed windows were used in this design. This is a reasonable alternative to higher cost vinyl double glazed windows. The outer windows on the sunspace were tinted blue. The blue tint serves to reduce the solar transmittance and the solar heating potential. The windows should be clear. Qinghai 3 40 30 20 Degrees C 10 0 -10 -20 Apr-00 May-00 Jun-00 Jul-00 Aug-00 Sep-00 Outside sunspace zone 2 zone 3 zone 4 Figure 10 Monitoring Data for Ba Zha Township Hospital, Qinghai Province Figure 10 shows the monitoring data that was made available for the Ba Zha Township hospital. Unfortunately we did not have winter data for this site at the time of this report. However, the building exhibits good performance. This can be seen from a closer inspection of daily temperatures in late September shown in Figure 11. 15  Qinghai 3 25 20 15 Degrees C 10 5 0 -5 2-Sep-00 6-Sep-00 10-Sep-00 14-Sep-00 18-Sep-00 23-Sep-00 27-Sep-00 Outside sunspace zone 2 zone 3 zone 4 Figure 11 Monitoring Data for Classic Sunspace Design Elements at Ba Zha, September 2000 The sunspace warms up in the day and cools at night. The rooms maintain a relatively steady temperature. Performance would be much better if the blue tint was removed from the south windows. No information was reported on winter coal use. It has been proposed that this building be renovated: increasing the southern window area and adding insulation. It would be good to monitor this building after the renovation. 16 Qinghai Solar – New Ba Zha Township Hospital The New Ba Zha Township Hospital is a modern passive solar building built behind the old hospital. The building has a 200 m2 floor plan with 9 rooms connected by a north hall. The building also included a solar PV system (not evaluated as part of this evaluation). The New Ba Zha Township hospital is well insulated, with 120 mm of foam insulation in the walls and 200 mm of cement vermiculite insulation in the roof. Nonetheless, numerous thermal bypasses through the tie steel, around the windows, at the roof skylight, at the roof gutter, and around the solar air heaters were found to reduce the performance of the solar heaters and of the building as a whole. In addition, the overhang was found to be too long for this climate as the windows were about 80% in shade in April, when the outdoor temperature is –5 deg C at night and highs during the day only 10 deg C to 15 deg C. These issues are presented with illustrated details in the annex. Qinghai Solar 40 30 20 Degrees C 10 0 -10 -20 Apr-00 May-00 Jun-00 Jul-00 Aug-00 Sep-00 Oct-00 Outside Zone1 Zone 2 Zone4 Figure 12 Monitoring Data for the New Ba Zha Township Passive Solar Hospital, Qinghai Province Unfortunately, we did not have data for the heating season at the time of this report, however Figure 12 gives a good indication of the thermal performance in late fall. When the outside air dropped to 0 deg C and –5 deg C in late October, the indoor temperature stayed around 12 deg C to 15 deg C with out any auxiliary heating. As the New Ba Zha Township hospital is similar in size to the Bain Tan Township hospital, the passive solar design may have saved between 15 and 20 tons of coal and between US$ 950 and US$ 1,250 in heating costs over the heating season. 17  Qinghai Solar 25 20 15 Degrees C 10 5 0 -5 26-Sep-00 30-Sep-00 5-Oct-00 10-Oct-00 14-Oct-00 Outside air out of mass wall air into mass wall Zone 3 Figure 13 Monitoring Data for Solar Elements at Ba Zha, Sept- Oct 2000 Figure 13 shows the room temperature and the solar air heater temperature in late September through mid-October. On sunny days the solar panel delivered air at 20 deg C and the room averaged 16 deg C to 17 deg C. The solar air heater has the potential to deliver hotter air, but the thermal bypasses at the edge of the collectors reduced the delivery temperatures. Conclusions for Qinghai Solar The building is basically a good passive solar design but suffers from high heat loss caused by poor insulation details. Areas of improvement in this design include: 1. Better insulation details to eliminate thermal bypasses. 2. Eliminate overhangs to improve spring and fall performance. 3. Train the building occupants in passive solar building operation. The doctors often leave the front doors open during the day, which cools the building down. 18 General observations on all the prototype designs All the passive solar designs were basically good solar design concepts, however each had problems in the small design details. Many small design flaws add up to very poor performance. The first thing to keep in mind is that a good passive solar building must first be a very well insulated, energy efficient building. Passive solar design features will not be able to heat a poorly insulated building. The following is a list of observations and recommendations that should be taken into consideration for the next round of building. 1. The basic structural design of all the prototypes contains many serious thermal bypasses. Thermal bypasses are gaps in the insulation. Typically, the structural design contains brick and concrete sections that provide a direct thermal path around the insulation. This reduces the overall thermal performance of the building by 50% or more. This is a serious problem that requires a complete rethinking of the structural and insulation design to avo id thermal bypasses. Conceptually, a thermally efficient building design consists of an inner wall and ceiling that is completely wrapped in insulation on the outside. Then, the insulation is covered by an outer wall or cement stucco or other protective covering. Ideally there are no thermally conductive materials connecting the inner wall and the outer wall. In some designs, steel is used to tie the inner wall to the outer brick wall. Steel is highly conductive and conducts heat very well. If large amounts of steel connect the inner wall to the outer wall, the thermal performance of the wall will be seriously compromised. If steel must be used to tie the walls together, then it should be designed to use the minimum required. Non-conducting alternatives to steel, such as reinforced plastic, should be explored for tying the two walls together. Solutions to this thermal design problem should be explored in depth with the structural engineers. 2. The insulation levels should be increased due to the very cold climate. A minimum of 100 mm of foam insulation or equivalent (R3) should be used in the walls and 180 mm (R5.4) in the roof. In the coldest areas, use 180mm (R5.4) in the walls and 250 mm (R7.5) in the roof. 3. The design and construction of the Solar Air Heaters (SAH) is poorly done and produces marginal performance. The site construction of SAHs may be too difficult for local contractors. If SAHs are to be used, they should be standardized to maximize performance. The SAH should not be a thermal bypass in the wall. Therefore the SAH should be installed outside the insulation. Uninsulated SAHs should not be used. The performance of the SAH panels will be significantly improved by adding a PV powered fan to move the air into the room. One fan should be used per room. The fans also help the performance of the sunspace by moving air from the sunspace to the room. A 12 Volt dc fan can be wired directly to the PV panel so the fan runs whenever there is sun. An on/off switch can be used to turn the fans off in the summer. Back draft dampers are required on all vents. The design of the back draft dampers should be standardized and possibly be manufactured to improve quality. 19 4. Overhangs in the coldest regions are not necessary. All the prototypes had overhangs that shade solar collector glazing in the heating season. 5. Building occupants and staff need to be trained in the efficient operation of a passive solar building. In all the prototypes, the doors and windows were left open during the heating season. The solar heat never builds up to heat the building because the windows and doors are left open. In general the prototype designs are too complex and cannot be built to perform well by local contractors. Site built SAHs, double- glazing, vents, shutters and insulation details were all poorly constructed in the field and therefore did not perform well. In some cases the materials selected for the solar components were inappropriate for the function. For example, on the Shanxi Solar, San Shi Li Pu Township Hospital, the SAH’s absorber was polystyrene foam insulation painted black. Polystyrene quickly breaks down in ultraviolet light and at temperatures over 40 deg C. The foam will be completely destroyed in less than one year. 20