Conceptual Design - Building Context & Passive Design

Journal Entry For
Module 4 - Conceptual Design - Building Context & Passive Design

For 2 or 3 units

  • (1) Create and share a Psychometric chart for your project location.
  • (2) Test 2 different alternative conceptual building forms using:
    • Insight analysis to predict the energy performance each of the forms
    • Solar insolation analysis to predict the solar radiation on the surfaces of the forms
  • Post images of the design alternatives that you modeled and the results of the analyses
  • (3) Explain your reasoning and the tradeoffs that influenced your decision about which design option to move forward with

For 4 units

  • (4) Given the conceptual form that you’ll be carrying forward, use Insight to determine the most important factors and their values that could deliver these performance thresholds:
    • Architecture 2030
    • Net Zero (if possible) or the best performance reasonably achievable

Building Site Context

I would like to propose Lake Chabot Regional Park, Castro Valley, CA as the project site for my Sustainable Exhibition Center. Some unique site features include the fact that it’s situated on the western slope of a hill overlooking the East Bay. Gorgeous view with some forestry on the eastern side to provide a nice backdrop. It is elevated from the surrounding suburbia, around 690 ft above sea level. The only neighbors are the San Leandro Hill Radio Site, although the only road to get access to this site is Fairmont Dr, which serves as the access point for the Alameda County Juvenille Hall. Hopefully the latter does not receive too much traffic so the existence of the exhibition center won’t cause congestion. The exhibition center can leverage its proximity to the Lake Chabot Regional Park by engaging park staff to engage in the exhibition center. A potential exhibit could be dedicated to the lake itself and how the built environment can work with the surrounding environment, or even support it.


The climate is quite temperate, considering the fact that it’s located in the East Bay, CA, with wind speeds that rarely go past 15 mph. It’s a perfectly comfortable climate that attendees can enjoy year-round.


(1) Psychometric Chart for Project Site Location


The closest available weather file for my location is at the Oakland Airport, which is approximately 5 miles west of my project site. From the Psychometric Chart, only 29% of the year would require active heating to ensure the building is at a comfortable temperature. Furthermore, no cooling is needed, which is a plus considering the goal of reducing energy use intensity. uncomfortable if there is no heating. Strategies to reduce the need for direct heating could include,

  • Southern facing windows
  • High-insulation materials (R-Value > 15)
  • Use of clerestories and skylights
  • Trombe Wall

(2.1) Building Mass Model 1


For my first building mass, my idea was to implement an interconnected mass with a sky-walk in the middle. I wanted something bold, hence the skywalk that interconnects the two building masses. The Western building has a sloped edge and on the flat surface, it will serve as an area where people can walk and see the nearby Bay. Since the Eastern side of the building is where it is sloped and covered by trees, I figured that it is ok that the same slope on the Western side is not duplicated.

This idea of a two-mass, but interconnected with a sky-walk idea, is meant to section off the exhibition center into two distinct areas for two distinct purposes. The flat surfaces on the top is ideal for the installation of PV panels and rainwater collection.


From the solar analysis, there is a great amount of PV energy production, particularly on the roof and S, W, and E walls. However, the Northern walls and the area underneath the skywalk would not be good for PV and would likely benefit from structural glass.


When running the model on Insight Analysis, without any modifications, an EUI that neared the ASHRAE 90.1 was achieved (54.9 kBtu/ft2/yr, which is 18% higher than the ASHRAE 90.1 value of 46.4). Considering the fact that no additional modifications were implemented, this is a good starting point. After making additional tweaks to the building mass using Insight analysis, the following was achieved.


A lot of tweaks were necessary to achieve Architecture 2030. In fact, the marginal reductions in kbtu/ft2/yr cumulatively allowed this mass model to reduce further beyond the maximum value of 20.8 kbut/ft2/yr for this mass model. Areas of adjustment included:

  • Plug load efficiency to 0.6 W/sf
  • Operating schedule limited to 12/6 to 12/5
  • Lighting efficiency to 0.3 W/sf
  • Wall construction to R38 Wood to 14” ICF
  • HVAC types limited to high efficiency heat pump to high efficiency VAV
  • WWR for Eastern walls limited to 30% to 0%
  • WWR for Western walls limited to 40% to 0%
    • Since the Western side of the building is what over looks to the Bay, I figured more windows may be implemented. However, installing an exterior facade that qualifies as a wall, but still allows daylight in and allows occupants to see the outside could reduce this WWR to 0.
  • Roof construction is insulated (i.e. uninsulated is not an option)
  • Infiltration limited to 0.17 ACH
  • Presence of daylighting and occupancy controls
  • Panel efficiency of 20.4%
  • PV surface coverage of 90%

(2.2) Building Mass Model 2


Although the initial mass model was more bold, I wanted to try something simpler. For the sake of conceptual mass modeling, I removed the skywalk since I don’t imagine that it made a substantial effect on the overall PV analysis by much. I sloped the walls and the roof towards south-to-north to further increase solar heat gain into the building.


From the solar analysis, we see slightly less solar energy generation compared to the initial model, despite having a southern sloping wall. This could be attributed to the fact that there is less roof area compared to the initial model. As usual, the northern facing side of the building receives the least amount of sun. To rectify this, I would imagine putting windows all along the southern wall to allow light to enter into the building and heat up the floor.

The shape of this building mass focuses on receiving sunlight. The sloped roofs and walls can be leveraged to have a natural way to collect rainwater at the southern floor of the building. Occupants, like building mass model #1, will have two distinct sections in the exhibition center to discover, with the middle void serving as a way to involve natural ventilation. The facades on the interior void of the building will be catered towards the fact that shadows are prone to occur. I imagine including multiple outdoor walkways in between the two buildings so that if any visitor wishes to step outside, be at higher altitudes, and get some fresh air, they can without having to leave the center.


When running Building Model Mass #2 on Insight Analysis, a similar result as that of Building Model Mass #1 appeared, albeit, with slightly higher values for the range (13.1 to 197.4 kbtu/ft2/yr versus 10.7 - 179.4 kbtu/ft2/yr).

Using the same Insight analysis assumptions for Building Model Mass #1, Architecture 2030 was able to be achieved as well.


(3) Choosing a Design Option

Based on the results of the insight analysis and the solar radiation analysis, I will be moving forward with building mass model 1. Building mass model 1 demonstrated the possibility of reaching Net Zero after making the multitude of tweaks as mentioned previously, whereas building mass model 2 did not (-3.7 kbtu/ft2/yr versus 0.9 kbtu/ft2/yr respectively). Furthermore, the Western sloped aspect of building mass model 1 is quite interesting and I believe a flat top surface could allow for more use-space flexibility. It could be a open space garden, or an exhibit itself, whereas it would be difficult for structures to be built on top of the sloped surface for building mass model 2. Lastly, building mass model 1 had a substantial increase in $ energy savings compared to building mass model 2 (i.e. a near $27k increase in savings). For the sake of reducing operating expenses, building mass model 1 also is an improvement over building mass model 2.

(4) Achieving Architecture 2030 and Net Zero

Section 2.1 already addresses the areas where building mass model 1 can achieve Architecture 2030, but even more adjustments are needed for Net Zero. The model adjustments that led to the largest impact towards EUI, a potential decrease of 10 kbtu/ft2/yr or more, involved:

  • Plug Load Efficiency
  • Operating Schedule
  • Lighting Efficiency
  • Wall Construction
Figure 1. Plug Load Efficiency of 0.6 W/sf for Building Mass Model 1
Figure 1. Plug Load Efficiency of 0.6 W/sf for Building Mass Model 1
Figure 2. Operating Schedule of 12/6 to 12/5 for Building Mass Model 1
Figure 2. Operating Schedule of 12/6 to 12/5 for Building Mass Model 1
Figure 3. Lighting Efficiency of 0.3 W/sf for Building Mass Model 1
Figure 3. Lighting Efficiency of 0.3 W/sf for Building Mass Model 1
Figure 4. Wall Construction of R38 Wood to 14” ICF for Building Mass Model 1
Figure 4. Wall Construction of R38 Wood to 14” ICF for Building Mass Model 1

Note that the four categories of EUI adjustments were not enough to bring the EUI of Building Mass Model 1 down to reach Architecture 2030 (see section 2.1), but it does highlight some key insights:

  • Appliances
    • The enduses of energy in my exhibition center will be incredibly important. Energy Star appliances, high efficiency lighting, and heat pump HVAC systems will be a must if my building is to achieve Architecture 2030, let alone Net Zero
  • Building Envelope
    • Implementing walls that are highly insulated will help prevent heat loss from the building, which is a must considering that 28% of the year requires active heating.
  • When the building is in use
    • This is an obvious one, but if the building has off days, then it can save more energy. Funny enough, this is the category with the highest impact, but the least desirable one. It would be sad to think that the best strategy to reach net zero for this building is to not have the building in operation at all.

To get into Net Zero, the following tweaks were made in addition to what was specified earlier in section 2.1:

  1. Adjust payback limit of PV to 20 years instead of 10 years
  2. Reduce operating schedule to 12/5 instead of 12/6
  3. Wall construction limited to 14” ICF
  4. HVAC system limited to high efficiency variable-air-volume system
  5. 0% WWR for Eastern Walls
    1. I figured this was ok since this was the side that doesn’t face the Bay and is towards the slope of the hill
  6. Roof construction limited to greater than R60 insulation
  7. Infiltration limited to 0.17 ACH
  8. Northern wall WWR limited to 40%
  9. Window shades limited to 1/3 window height to 2/3 of window height
  10. Adjusting building orientation so that the North side is 45 degrees from original 12 o’clock position

With all that was adjusted, the EUI still remains 1.47 kbtu/ft2/year. A significant improvement, but still not net zero. Further adjustments could have been made, but I felt like it would be too much of a stretch for some of them (e.g. 0% WWR for southern walls and western walls, when I feel like there would have to be at least some windows on these sides of the building).

The biggest takeaway from this Insight analysis is that to reach Net Zero, you need to look at all aspects of the building, not just the high-impact categories. There is no “silver bullet” solution towards net zero or architecture 2030 design goals. A designer must be meticulous and wise in their choices, lest they make a design choice that is way too costly or impairs other priorities such as occupant comfort or aesthetics.