Website started and updated by faculty and students of Cal Poly Pomona's College of Environmental Design: Department of Architecture.
AFFORDABLE HOUSING PROTOTYPE
Design Option1- Elongated on Nort/South Axis
• The floor plan as designed consists of two 24’x40’ modular classroom frames attached together to create a two bedroom two bath affordable housing unit.
• The unit also contains four cantilevered pop-outs extending beyond the frame.
• Fins and an overhang were added to the main east façade window.
• This helps lower the daylight factor to more reasonable levels
• Clerestory windows were added to the bathrooms
• Adds daylight, and provides natural ventilation
• Added pocket doors to the bathrooms
• Creates more privacy and lowers the amount of space for heating and cooling.
• Clerestory added to South façade (living room)
• Creates more daylight, and allows for better cross ventilation.
ASSUMPTIONS OF EXISTING CONSTRUCTION
• The entire structure must be made of lightweight materials.
• Support of the structure comes from a 4”x4” moment resisting steel tube frame.
• The floor system must be a raised concrete foundation.
Psychrometric Chart showing the available design strategies we can utilize.
Although Thermal Mass would be the most effective, structural limitations prevent it from being a viable option. Due to design restraints, many other options are not available. However, natural ventilation is, which helps reduce summer cooling loads.
We will be prioritizing sun shading and natural ventilation as strategies
• This graph illustrates that the heating load actually increased with double glazed low E windows. Perhaps a film on the glass prevents solar radiation from entering and warming up the space.
• Scenario 4:Triple Glazed
• An extra air gap allows for reduced heating loads, but costs make it prohibitive.
Utilizing HEED, we created 15 different scenarios which allowed us to roughly look at how various design and specification changes would impact the energy loads of the building.
One question that was looked at was whether or not it would be effective to build the structure above grade, or dig it out and place the foundations below. Using HEED it suggests that it would be more efficient to place the building foundation under grade. It must be kept in mind that digging out the foundations is more costly, and the yearly savings would only be less than 1%.
One specification modification that can be made which will lower the total yearly cost would be to upgrade from the minimum required HVAC system to one that is more efficient. The yearly cost would drop to $898.31- a savings of 9.7% compared to the base case.
Scheme 7 uses a variety of upgrades including increased insulation, a wholehouse fan, and a lowered thermostat (65 F-78 F). Compared to the base case scenario, we can achieve a savings of 29.5 % using these techniques
The Daylighting Analysis for the base case scenario shows that the bedrooms on the West side are already properly lit at an average of 4%. The main living space is well lit, with a bright area near the large east window and a dark area the south-east corner. The bathrooms do not have any natural light due to the lack of windows.
The modified project, which sees the introduction of fins and an overhang on the large E facing window, as well as clerestory windows in the bathrooms and the S elevation of the living room. These design changes create less intense light from the East window in the living space, but increase the light in the bathrooms and the southern portion of the living space.
June 21 – Shading Analysis
December 21- Shading Analysis
The Air Flow Rate Analysis looks at the wind speed inside and around the building, while the Flow Vector Analysis indicates the direction of the wind.
Because the wind generally comes from the south and west directions, it is important to look at and analyze the wind from both directions. Looking at both scenarios will allow us to test our design changes for either circumstance.
When the wind comes from the South direction in the base case scenario, it enters from the south facing bedroom, flows through the living space, and finally swirls around through the north bedroom before exiting. In order to create natural ventilation, the bedroom door must be open. Wind speeds remain relatively slow between 0 - .5 m/s with a few areas reaching 1 – 1.5 m/s.
The wind analysis for the south generated wind in our modified building is increased due the introduction of a clerestory on the South façade of the living space. The wind enters from this window, travels through the space, and exits via the windows on the north façade. The south generated wind flows through the space faster, averaging 1.5 m/s while allowing the bedroom doors to remain closed.
When the prevailing West wind his the Base Case scenario, it enters through the clerestory windows in the bedrooms, passes through to the main living space, and out through the large east window. This requires the bedroom pocket doors to be open. The north bedroom receives the fastest wind at 1.0 m/s due it having windows on both corners.
Monthly Heating and Cooling Loads for the Base Case scenario
The decrease when changing the windows to Double Glazed from the base case (single glazed) is also comparable to the results discovered in HEED. The change is only slightly noticeable.
When the windows are spec changed to Double glazed low e windows from the base case, there is a greater decrease in the loads when compared to double glazed. It is interesting to note that the cooling loads were decreased while the heating loads actually slightly increased; which is comparable to the HEED results.
When the construction quality is increased from the base case scenario, there is a substantial decrease in the heating load and a mild decrease in the cooling load. Increasing the construction quality consists of more airtight windows and doors as well as a better sealed building envelope. The dramatic results indicates that the construction quality is important in any building.
When the amount of insulation is increased to 1.5 times the base case, the decrease in the load is not as substantial as would be expected.
Looking at the Base case scenario for the average coldest day, the main living space peaks at a temperature of about 68 degrees, dips to 58 degrees, and averages about 62 degrees throughout the day.
When the same coldest day is analyzed in our modified version, there is an increase in the temperatures. The peak temperature is only slightly higher at 71 degrees, but the average temperature of the day increases to 65 degrees. The temperature in the Living Room plateaus as well.
For the warmest day of the year, the base case scenario reaches a peak of 92 and dips to a low of 80 degrees. The estimated average is about 85 degrees.
The modified floor plan shows only a slight increase in the average temperature. Again we can see that our modified building shows an evening out of the temperatures as compared to the base case.
• Base Case
o 2x4 wood framed walls
o Natural Ventilation: 5 changes/hr
o Single Pane Windows
o Asphalt Roof
o Ceramic tiles on wood floor (raised vented crawl space)
o Sealed Ducts 4.4 SLA
o Increased Insulation (2x6 wood frame)
o Natural Ventilation: 20 changes.hr
o Double Pane Low E
o Ceramic Tiles on Wood Floor (raised vented crawl space)
o Added 3 clearstory windows
o Added Fins and Overhang
During the summer months, while the outdoor temp. ranges from 63 degrees to 98 degrees , the interior of the base case is slightly better fluxuating between 71 degrees and 97 degrees.
During the winter months, the exterior temperature ranges from 42 degrees to 74 degrees, while the interior of the base case ranges from 58 degrees to 78 degrees, significantly warmer.
Looking at the average for the base case scenario, the building generally holds more mild temperatures as the exterior temperature varies greatly.
During the summer months, while the outdoor temp. ranges from 63 degrees to 98 degrees , the interior of the modified project is better than both the outside tem and the base case, ranging only from 71 degrees to 88 degrees.
During the winter months, the exterior temperature ranges from 42⁰ to 74⁰, while the interior of the modified project ranges from 58 degrees to 74.5 degrees, significantly warmer.
Looking at the annual average for the modified scenario, the building hold an even more mild temperatures than the base case or the exterior temp, ranging only from 65 degrees-84 degrees
Looking at the environmental performance of three possible choices for floor finishes will help us decide which is the better, more efficient choice. It is easy to see that natural cork parquet is the obvious choice when look at environmental impact.
The economic performance for the same interior floor finished indicated that both the BPS carpeting is the cheapest material, with natural cork parquet following after.
When weighing the economic and environmental performances equally, we can see that Natural Cork Parquet is the obvious choice for interior flooring.
Terrazzo generates the most Global Warming CO2/unit, while the BPS Carpets offsets it global warming emissions. Cork Parquet emits a low CO2/unit value.
All of the R-38 roofing insulation choices have relatively equal environmental performance. The Blown fiberglass insulation performs the best overall.
The Batt insulation is the best value as far as economic performance. It is interesting to note that none of the insulation has future cost.
When weighing the economic and environmental performances equally, we can see that Cellulose R-38 would be the best option. Because it is only slightly better, it is not critical at Cellulose Insulation be used.
Looking at the environmental performance of three possible choices for exterior siding. Cedar Siding has the lowest impact, and the greatest economic performance. If the decision were purely based on environmental performance, this would be the obvious choice.
The economic performance for the choices for exterior siding indicates that the cedar siding has the least economic performance. It is not surprising that the choice which has the best environmental performance also has the worst economic performance.
When looking equally at both the environmental and economic performance, vinyl siding emerges as a viable option because it is not terrible in either economic or environmental performance, rather it is mediocre at both. The Stucco has terrible environmental performance, while the Cedar Siding is terrible from an economic perspective.
The building as designed actually performs quite well. With relatively minor design changes and any of a list of specification changes, we can dramatically decrease the energy consumption, and increase the efficiency and sustainability of the Affordable Housing Prototype. Our design improvements include:
• New clearstory window in the South Façade of the living room. This would allow for increased ventilation in the main living space as well as provide natural sunlight from the South.
• New clearstory windows in the West facing restrooms. By installing windows in the restrooms, they are able to be naturally ventilated as well as be provided with natural sunlight.
• Install an overhang and fins on the large East facing window. Because this window allows for too much light/solar gain, a shading device minimizes this gain.
• Pocket doors for both bathrooms to allow for more privacy, and further control of heating and cooling spaces.
• Along with the many design upgrades that have been implemented, there were many specification changes that also dramatically improved performance including:
• Double Glazed Low E – 4.8% reduction in heating and cooling load
• Although triple glazed would further increase performance, considering the affordable component of the project, they would not be advisable
• 1.5 x Insulation- 4.7% reduction in load
• Greater Quality of Construction 37.5% reduction in load
• Well sealed windows and doors
• Tight wall to floor connections