Passive solar design concept for extreme climates
Energy effective passive solar design for buildings in complex climates
Heres everything you need to know about passive solar design for buildings in complex climates.
The passive solar energy design idea implies that the energy consumption of building designs is more effective. Weather conditions influence energy use and thermal comfort. Air distribution patterns, building envelope, radiation changes, and relative humidity determine the building and thermal environment. However, heat flow contributes greatly. The eventual heat-peak flux of each heat-flow collection hence determines the thermal performance of the passive solar design.
Sunshine and hourly and large diurnal variations in temperature characterize a tropical climate. India has a tropical climate and divides into 5 climate zones. In India, the Birla Institute of Technology constructed four rooms to find the best passive solar design. The following are the specifics of the building elements of these four rooms.
Study of thermal performance
The thermal performance of a building depends on variables of design, material characteristics, meteorological data, and data on the use of the structure. The numerous heat exchanges taking place in a building may calculate based on the basics of heat transfer and solar radiation. Heat moves by conduction, convection, and radiation from various surfaces. Furthermore, transparent windows use to transmit solar energy. The inside surfaces of the structure must absorb. People are present and lighting and equipment help to add heat to space. The thermal performance of the four rooms was equivalent to the general heat load using constant static techniques.
Considerations made for calculations,
- Considered a clear sky.
- 12 km/h wind velocity assessed.
- No internal heat in the rooms as they were empty.
- No ventilation.
- The heat gain is attaining only through solar heat gain and conduction.
Monthly thermal performance analysis
For 365 days in the year from dawn to sunset, the total solar radiation on all surfaces is estimating based on the ASHRAE model. On all surfaces, it was determined the average daily solar radiation. Radiation from rectangular shading on windows and planned static sunshade was estimating for eastern, western, and southern walls. The computations used Excel VBA codes. The curve approximating by three straight lines for the convenience of calculations to determine the shadowed area of the window owing to the proposed static sunshade.
For each building component of the four rooms, the product AU computes. U shows the total heat transferred per unit area per unit time from the outside air to the inside air through a certain wall or roof. The smaller U is, the higher is the element’s isolation value. The U-value may therefore use to compare the insulating properties of different components. The stable state technique does not take the influence of building materials’ thermal capacity into consideration. The equation has supplied to U.
The temperature of the sol-air (Tso) was determined using an equation utilizing the average daily outside air temperature and the average daily solar radiation.
The heat flow rate via the building enclosures (Qc), is the total area of all parts of the building and the U-value products multiplied by the difference in temperature. It is has expressed in the same way.
The solar heat gain from windows and the thermal conductivity of all four rooms have estimated based on the approach given in Section 3.1. In the light of the impact of sunscreen, the solar heat gain from southern, eastern, and western walls has computed for each room. The solar heat gain for these three rooms was the same, given that windows, sunshades, and their orientation was the same for the R2, R3, and R4.
The solar heat in R2, R3, and R4 were greater in February, March, September, and October than in R1 between November and January, and R1. However, R1 was lower than that of R1 in R1. The static sunshade on the window on the south walls of R2, R3, or R4 rooms may ascribe to this, which provides more sunlight in temperate winters and less during moderate summers. From April through August, all rooms received solar heat, as the sun path changed to the north. The static sunshade on the south wall above the window did not modify the entrance of solar light via the window.
For each building component of the four rooms, the product AU has computed. For rooms R1, R2 (117.54 W/K), the product AU was highest while for rooms R3 was 87.65 W/K and R4 less (68.46 W/K). This was because of the planned passive solar features. It figured that the sol-air temperature estimated and the total conductive heat charge per room. The thermal charge of the rooms R1, R2 was identical to those of the building elements by which the thermal load of both rooms has computed.
Due to the static sunshade constructed, the heat load in room R2 was higher than in-room R1 during the winter months. With brick cavity projections the overall heat load of room R3 was considerably lower than that of room R2. The heat load in room R4 was smaller than in-room R3 all year long due to the influence of the hollow roof. Because of the combined impact of planned passive solar design components, the thermal load in room R4 was lower than in room R1.
Analysis of thermal performance on typical days
The heat performance of the rooms in different seasons of the year had compared with typical crucial data. The interior air temperature and the outside air temperature have 24 hours a day at one-hour intervals. The seasonal categorization was based on the highest and lowest values of the average outdoor air temperature each month throughout the year.
The air temperature outdoors for each of the four seasons led to selecting the four dates. Every season. Here, it found extreme, and most common temperature values day and night. The day taking from 0600 – 1800 hours while from 1900 – 0500 hours considering. In the moderate summer and summer, the maximum temperature was showing to be extremely high. However, in the mild winter and winter, the lowest temperature was the highest. By determining the frequency distribution of the outside air temperature, the extreme and most common temperature values were determined.
Then it selects the most valuable one for moderate summer and summer. The lowest value was select in mild winter and winter. Day and hour for maximal direct, normal radiation were determined in mode. In every season of day and night, the heat charge conducted and the solar heat gain in the four rooms was determined at each of their extreme temperature values. Each season based on total heat load conducted analyzed thermal.
Day and night distributions of outdoor air temperatures across the four seasons, meaning that summer was moderate, summer moderate, winter was mild. It extracts the mode and extreme values of each season, calculating the overall heat load. On four typical days in the four seasons, a sum of the heat load on R1, R2, R3, R4 was determined (Figures 8-11). In summer there were 7 instances of mode value on different days. The temperature outside the air was often 35.70C.
The sun radiation value was at a maximum of 1300 hours on 28th May. Therefore, the heat load calculates. The thermal burden on room R4 was lowest (2244,47 W) while passive solar elements were the highest for room one R1 (3498.64 W).
Throughout the summer the greatest temperature detected (45.40C) at 1500 hours on 7 June. Room R4 had the least heat load (2820.10 W). The total heat charge throughout the daytime (25.10C) and the night (23.90C) for the most common temperatures during moderate summer has not had estimated, as the outside air temperatures are well within the comfort zone.
Utilization was done in Autodesk Ecotect Analysis 2011 software to simulates and compares the rooms. The Chartered Institute of Building Services Engineers utilizes Autodesk Ecotect Analysis 2011. Method of admission to determine interior and thermal temperatures. The Autodesk Ecotect Analysis 2011 thermal models are based on the spatial organization of distinct areas. The website of the U.S. Department of Energy provided the climate variables utilized in the simulation weather file for this meteorite near the experimental set-up.
Assumptions related to modeling the rooms,
- Non-thermal zones are allocated thermal properties of shades.
- Did not simulate tools that were obstacles to modeling and thus windows metal frames.
- Assumed homogeneous distribution of the thermal mass on the walls of room R3 throughout the whole wall.
- Designed windows with special materials, to open the walls of room R3 as windows.
- Modeled hollow R4 roof as a single layer of stoneware material by substituting stoneware pipes.
- Received weather information from an external source and did not collect the remaining experimental restrictions.
This developed a zone tool for Room R1 thermal. For the sunshades and plinth, constructed separate non-thermal areas. 100 mm thick concrete plates used to make floor material, while for the roof, 100mm RCC thick plates utilized, topped with 25 mm thick concrete plaster, 5 mm thick, and 20 mm thick ceramic tiles. Room R2, other than the sunshade on the south wall, this modeled in the same fashion as Room R1.
This simulated the shadow just on the bottom surface. In Room R3, the hollow walls have fitted with a new material consisting of a 113 mm thick air gap, sandwiched between 112,5 bricks. This modeled the projections on non-thermic zones. Their thermal mass uniformly dispersed throughout the main walls to account for the increased shade and thermal mass owing to brick projections on the west, east and south walls. So, according to the brick projections, it increased the thickness of the external layer for all three walls.
The aperture in the wall mimicked a window consisting of an air gap as an exterior layer and an inner layer of 112.5 mm brick masonry. The simplification is possible, and it might have produced a difference from the real results. Room R4 designed for Room R3 was assuming that the distribution of air cavities and piping material will not alter the thermal performance of the roof. Considerably while modeling the hollow roof of room R4 roof. Then they modeled the stoneware pipes into one layer as a continuous mass. Likewise, this aggregated the air cavities into a different layer.