1. Building Performance:
The first step, to help decide what materials and design features the building envelope should include, is to look at the current building performance. The Autodesk Insights tool shows that with no changes, and using the current BIM settings, the building has an EUI of 58.5 kBtu/ft2/yr.
1.1 Building Orientation
In previous models, it was decided that the two smaller ends of the Y building would face towards the south, to maximize the winter sun. This would allow for the best passive solar heating in the colder winter months. However, for simplicity thus far, these walls were facing the North. Before rotating the building orientation 180 degrees, I checked to see if my prediction was in fact accurate. As shown below, you can see that by rotating it into the orientation decided upon in the earlier models, the buliding would lower its EUI by 3.5 kBtu/ft2/yr.
Before:
Rotated:
The lower winter sun means that the sunlight penetrate the building better in the colder months. Additionally. this siginificantly increases the roof area facing the sun, and is thus the better orientation for solar panel efficiency.
1.2 Wall Construction
Exterior Walls:
As shown below, the currently used standard exterior walls in Revit do a decent job at lowering the EUI, however there is significant room for improvement if wall designs with a higher R-value are chosen.
The best insulating, weatherpoof and cheapest wall designs included concrete. However, after studying the Y2E2 wall construction, I discovered that using prefabricated concrete masonry units rather than fresh concrete would lead to far more building materials used (one of my big project goals). As for the insulating material, after some research I discovered that Sheeps Wool is a natural material that boasts great insulation properties, and is being used more frequently. I thus opted for this as one of my insulation materials, to continue the trend of using sustainable materials.
When creating this new material in Revit, I found a technical sheet (linked below) for Black Mountain Sheep Wool, which provided all the necessary thermal and density inputs to accurately model the material.
Below is the final structure of my exterior walls. As you can see, I have significantly increased the R-value of the walls to 31.9 hft2F/BTU. This will help reduce the EUI of my buildling, as the climate analysis in the earlier modules showed that heating in the winter months will be the biggest consumer of energy.
Interior Walls:
For the interior building walls, I went for the basic wall structure in order to reduce materials used. As I do not require a high R-value for the split between internal rooms, I used this opportunity to be more cost and environmentally efficient
For interior walls, I have gone with a basic interior wall, to reduce the material usage and keep costs at a minimum. The lower R-value does not have a significant enough impact on th
1.3 Roof Construction
As the insight analysis showed, the standard roof construction I had initially modelled my building in, provided sufficient insulation. There was no need to expand any further.
This basic roof structure was chosen, and it’s high thermal resistance provided sufficient insulation to keep my site EUI low.
I decided to add a green roof for my rooftop-terrace, as one of my key goals was to provide a green, natural environment and boost mental health at the same time. This has the added benefit of helping cool the building in hot summer days, and insulate the building heat further during the winter months. Note that this reduction in EUI was not included in the Insight tool, as it was modelled as a ‘floor area’. The planted trees not only provide an aesthetic and natural look, but also provide shade for the seating and viewing platform (for details, see the model screenshots below).
1.4 Windows/Curtain Walls
North Facing Curtain Walls:
The North facing curtain walls are the most interesting of the building, as at the ground level to second floor they are perpendicular to the floor. After the second floor, they slant inwards, connecting with the roof at an angle.
As the North face of the building gets a lot of sun during the summer months, it was important to consider shading and glazing. For the latter, I have invested in triple glazing with Low-E. This helps with the thermal resistance of the building during the colder winter months where the sun is on the south side of the building. I want the atrium of the building to be bright and connected to the outdoors, which is why a clearer glass was chosen.
Due to the clearer glass, shading had to be considered, in particular for the summer months. As the top part of the curtain wall is exposed to the high midday sun from above, horizontal ‘mullions’ were considered. This is mroe effective at shading the atrium during the hot midday sun. Timber was chosen as the material, as it is both sustainable and natural, adding to the aesthetic of the building.
During the early mornings and late evenings, the sun hits the front panels more than the top panels. Due to the low position of the sun in the East (and West), vertical shading was used for this curtain wall.
South Facing Curtain Walls/Side Windows:
For the rear windows in the building, the winter months had to be considered most. As the winter sun hits these windows, this is a great opportunity for solar passive heating. Hence, double glazing was chosen with a low-E glass. This provides sufficient insulation, but has a higher heat transfer coefficient. Clear glass is optimal for daylighting, and providing a gateway to outdoors for aesthetic purposes.
As for window shades, vertical timber mullions were used. This is because when using the sun-path tool in revit, it was discovered that at its strongest, the winter sun is located between the two wings. Thus vertical shades would prove to be most effective at reducing direct glare. This was an important factor as these wings host the exhibition spaces and office spaces, both of which should avoid glare/too much direct sunlight.
The windows on the side of the buildings used the same double-glazed features as the rear windows.
1.5 Floor Construction
Ground Floor Slab:
As the ground floor is in direct contact with the soil and surrounding ground, insulation for the winter months a key consideration. By using a concrete precast masonry floor slab with sufficient damp proofing and insulation, I could ensure a sufficient thermal resistance to keep the building warm in the winter months. Additionally, concrete would cool down over night if the building is ventilated in summer, and could then be used to cool the buildilng during the day, a passive cooling strategy currently employed in the Y2E2 building.
For the first and second floor, a standard timber floor as been selected for its sustainable material usage, and aesthetic beauty that matches the theme of the building.
Outdoor Cafe Patio:
The outdoor patio area is prone to change, but for now a single concrete terrace wa schosen with a metal deck underneath. As it is outdoors, there was no need to prioritize a material with a higher R value.
1.5 Doors
The external doors following the same principles as the windows. On the north face of the building, they all have double glazing with a low clear E glass. Indoor however, the doors use single glazed class, as I do not expect much of a temperature difference between neighbouring rooms and therefore can save on costs by not overengineering the design.
2. Changes to Building Performance:
The above mentioned design changes were all conducted in with simultaneous checking of the Energy Insights tool. Once complete, the building performance has been significantly improved. As shown below, by setting all categories to the latest BIM settings, the EUI has been reduced significantly.
The changes to building envelope has lowered the building EUI to 21.2 kBtu/ft2/yr.
So even without Solar Panels and Efficient HVAC system, already an Architecture 2030 buildling, which was one of the main goals outlined for this project.
Further Energy Saving:
Adding solar panels to 75% of the roof area (leaving the excess 25% for HVAC and maintenance), with a 20.4% panel efficiency and a 20 year payback limit, we reach the following EUI. Additionally installing an ASHRAE Package Terminal Heat Pump HVAC system, the building achieves the following EUI: -4.75 kBtu/ft2/yr.
3. Lighting Analysis:
The Revit Cloud Render tool was used to produce Illuminance Renderings of three key areas in your building model. These three areas are being presented, as they show the three different lighting situations in my building (standard, high and low lighting levels)
Cafe Interior:
The cafe interior below shows an ideal level of lighting. At 3pm on a summer day, the average lighting is about 40 - 60 fc (legend can be found in the last photo).
While 40-60 may seem like a significant value compared to the 20-30FC recommended in the source below, it is not an uncomfortably high value (approximately the level of a classroom), and this was measured during the peak summer. In the winter months, the sun path falls on the south side of the building, and thus a much lower value is expected.
The room below is on of the exhibition areas, in the rear wing (south facing side) of the buildling, again during a summer afternoon. As you can see, the majority of the room has a very low level of lighting (0 - 20 fc) This is perfect, as I wanted a dimly lit setting that is frequent in museum exhibitions. This means that you can create atmosphere and ambience manually, depending on the exhibition being displayed. In the winter months, the sun will brighten this room, however the vertical shades will have a mechanical feature that will allow them to close partially, to give the building owners control over the mood daylighting in the wing.
The final room is the main lobby/atrium of the building. Due to the curtain wall on 2 sides, the entrance is very well lit (100 - 200 fc). While this is slightly high, this was also reported on a June afternoon, with the sun shining directly in the room. The shade angles could be adjusted to lower this, but it is also a room that will not warrant any idling, and thus it is not crucial to set a perfect lighting level. The first floor corridoors on the side, display a range of 0 to 60 fc. This is ideal for summer months, however in winter this will be reduced signfificantly with the sun shining from the south side, so artificial lighting is crucial in these areas.
