Cambridge Year 3 - Architectural Engineering

ARCHITECTURAL ENGINEERING: INDIVIDUAL REPORT OLIVER BALDOCK

The design developed around the desire to reference the existing roof and the original structure. Our initial reaction was to maintain the proportions of the space and the existing frieze as key elements of the space, intrinsic to its unique character and architectural value as a distinctive spatial experience within the museum. As the design progressed, a more rigorous consideration of the original roof led to an interest in how the relationship between curved and orthogonal elements could be harnessed to generate an authentic yet contextual spatial experience. i: 1:100 model of internal roof structure.

3d printed base from CAD Model, by David Turner, roof modelled by Oliver Baldock

ii: Early iterations of roof design.

Group decisions, modelled by David Turner.

THE STRUCTURE OLIVER BALDOCK

The structure is entirely glulam and the connections are entirely timber. Without any codes for the design of these timber joints an innovative solution was required. This involved adapting existing steel connection methods to timber, ensuring the joints carried mostly compressive forces and little, if any, moment. The curve of the primary columns is defined by the maximum radius that the required thickness of glulam can be bent to, with infill pieces used in places to accentuate the curves of the members. The secondary structure is in the same plane as the primary to create an elegant bracing system. It sets up a centralised geometrical order more common to circular or oval spaces, letting us to span the space in the short direction whilst preventing any dominant directionality in the space allowing it to be accessed and experienced from three directions. i: Construction details

Construction details by Oliver Baldock

ii: Axo Sections through CAD model

By Oliver Baldock and David Turner

ii: Later iterations

Group decisions, modelled by David Turner

LIGHTING STRATEGY OLIVER BALDOCK

The majority of the light enters at clerestory level, with additional lightwells bringing natural daylight through the three oval skylights. As the curving primary structure ‘peels’ away from the orthogonal regularity of external enclosure, light is allowed to enter the space. This is as similar stratedy to the existing roof, but whereas the existing windows have been covered in both curtains and a UV protective coating, our design prevents light falling on the paintings by limiting the angle at which is can enter at clerestory level. As shown in the section above, the current height of the paintings can be maintained without any need for additional UV filters or other lighting protection. This, along with diffusers beneath the skylights provide a daylight factor of just under 3%. We found this an appropriate level for the gallery, whose curators had previously mentioned their desire for controllable artificial lighting to accentuate each of the paintings individually. The louver design is identical on all sides so as to emphasise unity within an already complex spatial experience. i: Lighting inside 1:100 model

1:100 Model by Oliver Baldock

ii: 1:20 Sectional model of louvers and window

By Oliver Baldock, David Turner, and Henry Robinson

iii. Initial louver sketches and checking of lighting angles

By Oliver Baldock and Henry Robinson

VENTILATION STRATEGY OLIVER BALDOCK

The natural ventilation strategy works using a roof level plenum, with external vents at high level on the edges of the roof and cut into the existing external wall at low level. In summer, the air enters through the lower openings and leaves the main space through the oval skylights, before being finally expelled from the plenum by the high level vents within the roof structure. Natural ventilation, as shown in the calculations, is insufficient, so there would need to be a hybrid system of fans within the plenum helping to drive airflow, in order to reach the required ventilation rate. However, there are only 14 days a year when the temperature is above the allowable maximum which suggests the use of a hybrid mechanical system is easily justified when compared to the systems currently in place.

In winter, the low level vents would be closed to create a mixing ventilation strategy where heat exchange can take place within the plenum before entering the space through the skylights. It should also be mentioned that all calculations considered an occupation of around 100 bodies in the space which is not currently a common occurrence for the gallery. It does not include the effects of thermal mass on the temperature in the space. i: Ventilation strategy

by Oliver Baldock

ii: Initial ventilation calculations

by Oliver Baldock, included within appendix

iii. Advanced ventilation calculations By the enginners, included within appendix

CONSTRUCTION DETAILING OLIVER BALDOCK

Tiling / Protection Layer for access to skylights Filtration Layer (for runoff ) Insulation Waterproofing Plywood (and 1:50 Leveling) Glulam I-Beams (and plenum) Plywood / facing wood

Double Glazing Window Frame Waterproofing Layer

Perforations through the beams in the plenum

Plaster Plywood Insulation Plywood Air gap (potential further insulation)

The roof level plenum consists of glulam I-Beams perforated to allow the mixing of the heated air from the gallery below to rise up into the skylights and mix with the cold air drawn in through the vents. These perforations, as shown in the sectional model, also include a mechanism to reduce the size of the openings thus reducing the amount of heat lost during the cooler months. The construction details above describe the inverted roof where the insulation is above the waterproofing layer and protected by boarding. The shallow 1:50 gradient allows run-off into the concealed gutter which then travels to each of the four corners to use the existing drainwork. The glazing hangs from the roof which is supported by the primary beams rather than the stud walls. This means the stud walls which come to meet the bottom of the glazing and surround the main structure do not need to be structural themselves, and consist of two stud walls and an air gap in order to bridge the 1m depth of the existing wall structure. This stud wall also works well to hide the concrete work connecting the primary and secondary beam to the existing wall structure. i: Construction details

by Oliver Baldock

ii: Connections and fixings

by Henry Robinson

APPENDICES OLIVER BALDOCK

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Initial calculations by Oliver Baldock Graphs and details by engineers.

Initial calculations by Oliver Baldock Details by engineers.

AVERAGE DAYLIGHT FACTOR

Average Daylight Factor Calculation DFave = (T.W.d.M)/(A.(1-0.5²)) Vertical Glazing T = 0.72 W = 247.69m² G Ü M = 0.85 A = 1434.56m² DFave = (0.72 X 247.69 X 16 X 0.85)/(1434.56 X (1-0.5²)) = 2.25% Horizontal Glazing T = 0.72 W = 15.49m² G Ü M = 0.85 A = 1434.56m² DFave = (0.72 X 15.49 X 69 X0.85)/(1434.56 X (1-0.5²)) = 0.61%

Total DFave = 2.86% Final calculations by Henry Robinson

VENTILATION

Aim: Fully naturally ventilate The Fitz.

Reality: Not realistic. Tight constraints on temperature, humidity. Adopt a hybrid system, conserve energy.

Requirements are 18 – 24 degrees with < 5 degree daily variation and 40% to 60% relative humidity with a daily variation <10%.

Natural Ventilation Concept: Below are the theoretical ventilation strategies, section view. All vents contain fans and can be closed/opened automatically to control air flow. Recognising that natural ventilation is a bit of a dark art, a computer controlled self-learning and regulating environment with a high number of sensors will be used.

Vent Sizes Bottom – 3.21m2 minimum ~16 vents required @ 4m centres along the floors. Cut through the walls/utilise old vents too

Top – 3.21m2 minimum ~7 vents required, although these vent may act as top or bottom depending on flow.

Place these above windows between every other primary beam (3 on each side) plus one on each)

Roof light – 3.21m2 This is more difficult to do but will cover the entire bottom 10cm of all 3 the roof oval lights to give approximately the correct area.

Undoubtedly the ventilation area is over specified, particularly since we are using fans within this ventilation to help control air flow. Over specified gives room for climate change, miscalculations and freedom to change to strategy if required.

Heating: Underfloor heating will be installed during the rebuilding of the gallery.

Cooling: It is calculated that with fan assisted natural ventilation, there is no need for air conditioning units to be used in this gallery, although one might like to make provision for a unit in the event of unforeseeable circumstances.

Humidity: The gallery now has a timber roof and untreated timber wall panels complimenting the wooden floor.

These together should act as a ‘sponge’ for humidity however; a humidifier and dehumidifier will also be required to maintain the necessary relative humidity and will be specified by the contractor.

Further, it is shown that indoor plants help regulate humidity levels and so the gallery will be festooned with plant life whilst being careful to not damage the precious paintings. Summer plants perhaps will help people to feel warmer in the winter months.

Natural Lighting: Vast amounts of natural light now penetrate the gallery but careful design has ensured that none should be directly concentrated on the paintings. When the museum is closed, blinds will cover the windows automatically to lower light dosage.

Artificial lighting: Lighting will be used to further enhance the third dimension of the paintings. This gallery provides a massive amount of daylight, but none directly to the paintings. Low energy LEDs will be used, hung from the oval light wells in the ceiling. The intensity of which can be varied to tailor to the requirements of the painting itself as well as the natural light. This will be controlled using the smart light dosage meters on the painting frames which measure the light dosage to the paintings. The LED lights will also be connected to the main system which will turn them off when visiting hours are over to lower the light dosage to the paintings.

Control system: This will be a SMART gallery, with a centrally controlled computer system which learns the environment and controls all aspects including lighting, airflow, humidity and temperature.

Innovations: Dosage meters attached to the frames of paintings monitor and record the amount of light that the paintings are being subjected too. It will tell the museum if one painting is receiving too much light and then things such as lighting can be adjusted or the painting can be moved into storage.

Circular sofas will sit in the room, allowing the public to rest whilst gazing at the paintings. Inside these sofas will be a tree/plant which will not only liven up the room, but also help control humidity.

Final Ventilations conclusions by the engineers,