Participant Report

General Information

Competition Entry Id: / 132
Project Name (your description): / Square arena 132
Country: / France

Further Details

Was DesignBuilder Optimization used? / yes
Was any other optimization tool used (e.g. JEPlus)? / no
Estimated time spent on competition (optional) / Human time 40 hours - machine time > 300 hours

Floor Areas

Fill in the table below with values reported in the CSV report
Total floor area [m2] / 2996
Office floor area [m2] / 2402
Of which cellular office area [m2] / 321
Utility area [m2] / 423
Circulation area [m2] / 171

Results

Fill in the table below with values reported by DesignBuilder as explained in the document DOC_Brief.pdf
CO2 Production [kg] / 138161
Building Total Cost [GBP] / 3414102
Discomfort (all clothing) [hrs] / 137
Daylight Floor Area above Threshold [%] / 51

Architectural Choices

What is the form of your architecture, and why did you choose it? You may use images and diagrams to explain the concept.
My ambition was to design a building without active mechanical cooling needs and a very little heating load.
I wanted to be as close as possible with “passivhauss” requirements.
Reducing heating load impose a compact building desing. I first choose a cubic shape.
On the contrary, a daylight factor greater or equal to 2% over at least 50% of floor area imposes either a not to deep building level or a distributed zenith natural lighting.
I chose à 3 floor building with a square basis, a wide glass closed central atrium in a starecase shape.
I positioned light-wells on the internal roof (into the glass closed atrium) of the first level to guarantee a sufficient daylight factor on this level (the wider). The other levels are thinner and are enough lit by the peripheral windows (inside in the central atrium, and outside).
The third level has just a part of the surface of the second. It is positioned on the north side to allowed daylight to get widely into the central atrium.
The surface of the windows were conditioned by optical qualities of the glazings and the daylight factor.
I chose the most powerful triple glazing from the thermal point of view while preserving a good optical factor for the external glazing, and the most transparent double glazing for the windows giving on the covered atrium.
The building is positioned just at the limit near the crossroad onto escape the maximum with the shade of the surrounding buildings on east and south.
Daylight management was the first real hard point in the design of the building.
Utilities area, Circulation and stairways are on the north façade. Cellular office are on the south façade.
the central glazed atrium acts like a space buffer usable most of the year for relaxation for example.
/

2nd design - Daylight principle

2nd design - Natural summer night cooling principle

Describe the key points of the project:

Use this section to describe the key design decisions you have made, and why. Please highlight the most important points in a succinct way.

Construction

How did you choose the constructions and materials of the building fabric in your design?
Daylight need impose large glazed surfaces.
A very low heating load building need a very good insulation. Exterior surfaces needs to be well insulated, external glazed surface have to be high performance.
The glazed roof on the central atrium must left a maximum of light for the daylight needs. That is why it is composed off clear uncoated double glazing. Offices glazing on the atrium are the same for the same reasons. There are no real need to have high efficiency glazing here because the atrium constitutes a buffer zone between inside and outside. The atrium can be use as an ease of use zone during most of the year.
A building without mechanical cooling device, needs to store excess heating due to activities (lighting, occupancy, equipments) and solar contributions during days. The building must have a heavy structure. Night is useful to take out stored heat via natural ventilation.
The outside skin must be very well insulated to avoid heat loss in winter and heat gains in summer.
The need of a heavy weight well insulated skin is not realy accurate. We can use à light weigh well insulated skin to. Optimisation was done between these two solution. Well insulated SIPS wall were choose for cost reasons and for the ability to manufacture these panel in a workshop. The set-up time on building site is then reduced.

Systems

How did you choose the HVAC system, lighting, ventilation strategy, and shading devices in your design?
I select the LTHW radiator heating because this system is quiet simple, needs few outside and inside space, has good performance even with extreme outside low temperature, has a low carbon footprint in term of use. The definite choice was made after comparison with the others heating systems via DesignBuilder Optimisation.
I choose “T5 with linear control” because it has good performance for a reasonable cost.
Shading devices are use for cut off exceeding solar gains on to avoid overheating.

Controls

Describe how you designed the control strategy and/or chose the control schedules and set points.
Heating set-point temperature was choose by DesignBuilder iteration and needed to be comfortable and as low as possible CO2 emitting. Better results were found with an internal set-point temperature of 21°C.
In practice, an integral simulation with designBuilder need to set the temperature to 21°C to achieve comfort requirement.
Ventilation is set to the minimal requirement in occupation. It is off in in-occupation during the cold period. Natural ventilation is set on when interior temperature > 24 °C.
Overheating management is less simple when there is no mechanical cooling system. We have to control sun energy input during hot sunny days and accurately use the difference in temperature between inside and outside. (solar setpoint < 120 W/m2)
The internal mass of the building will be used to smooth the temperature rise by storing surplus heat. Night natural over-ventilation will be used to eliminate mass stored heat.

Design approach

Use this section to describe the approach you have taken, that has led to the final decisions. You can also show how your design evolved through the process, for example, the sequence of decisions on form, construction, systems, and control were made.

1st design : compact design to minimize heat loss

=> not enough daylight, building to deep
/

2nd design 3 storey and a bigger atrium

=> not enough daylight,

3nd design – an attempt to maximize daylight

=> daylight OK if light-well are positioned on the roof of the first level, but big heat losses
/

4nd design – an attempt to maximize sun gains

Heat losses OK but daylight under requirement due to neighbour buildings

5nd design – definite design

Heat losses OK, daylight OK
/ On this last model, I've made an optimisation search for the heating system and for the optimal setpoint temperature that meets comfort and minimize energy consumption (CO2 emission)

Any Other Supporting Information

Comments and feedbacks

Anything else you would like to say from the experience of this competition? Your comments and feedbacks on the challenges of real world design problems, availability of tools, and the organization of this competition would be very welcome. Contents in this section will not affect your score.
Competition was very interesting. I discovered the real impact of daylight on the final design.
I think, the projects are basis to work on to minimize energy consumption. Therefore, circulations, staircases, utilities area can have different settings (confort, daylight) that can even more emphasise building energy efficiency.
Optimisation tool is interesting, but very time consuming.
I am personally interest to have further discussion on the winners projects and on DesignBuilder as Colin Lillicrap propose in the forum.

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