What are the environmental drivers for building form?
Early engagement with a MEP / environmental designer can help provide initial ideas from which an architect can respond. This performance-led approach can create a solid foundation, ensuring that the scheme reduces energy use whilst improving health and well-being.
This approach also reduces the likelihood of a scheme falling in the ‘sustainability post-rationalisation’ trap, whereby a sustainability story is concocted after the design is largely fixed.
Here are seven potentially fruitful environmental design drivers for building form:
Solar is one of the main environmental drivers for building form. The sun’s position is accurately known throughout the year which means the form can respond in a very precise manner to building needs such as daylight, passive solar gains in winter and solar shading in summer.
The provision of good solar amenity can help lift an occupant’s perception of an entire scheme and simulation tools can predict where sun and shadows will fall throughout each day and across the seasons.
As an example, the simulation below quantifies the ability of a large dynamic solar shading device to reduce summertime solar exposure.
Knowledge of the local wind conditions can shape the design of a building. For example, it can passively help supply fresh air as well as help meet summer time cooling needs. Yet it is rarely used effectively because the ability of a building to harness the wind is highly form dependent.
Wind is more unpredictable than solar but never-the-less there are tools we can use to simulation wind flow models, as shown in the image below, in order to reveal the wind landscape and drive design.
Wind is also a driver for pedestrian comfort. This can involve taking into account the prevailing winds to avoid unwanted acceleration and downdraughts from tall facades. Massing decisions can create sheltered and highly desirable spaces especially when combined with solar amenity.
Renewable energy can often provide a substantial proportion of local energy requirements. However, the potential impact of renewable energy generation depends on the early strategic input. This is because the main renewable technologies of solar PV, solar thermal, wind energy and geothermal are highly form dependent.
For example, a building form can maximise the amount of unshaded area for solar PV panels. In the case of solar thermal, the building form can allow panels to be mounted at a high angle. This means more panels can be deployed, as summertime overheating is avoided). It also means that more hot water can be generated for free earlier in the year as well as improving self-cleaning via rain fall.
Night cooling is a highly effective passive means of reduce or eliminating the need for active cooling. It is an extension of wind design consideration, involving both form and fenestration. However, it is also involves developing a strategy for thermal mass distribution as effective night cooling requires both night time airflow and a means to store coolth for the next day.
In the example below, our strategy involved creating three heavy-weight thermal-store stair-cores which act as night-time coolth batteries. A Dynamic Thermal Model was used to quantify the benefits following standard such as TM59 for residential area and TM52 for commercial spaces.
Passive evaporative cooling can provide very low cost and low carbon cooling. However, it can be rarely used because the building form and servicing strategy have several design requirements in order for this to work. For example, evaporation may have space requirement. Also an evaporative-cooled space needs to be separated from actively-cooled spaces. The illustration below, in section 7, shows how we integrated evaporative cooling into the design of a pavilion.
Demand Side Response (DSR)
Buildings can be designed to take advantage of Demand Side Response (DSR) schemes arising from financial incentive provided by National Grid to control frequency and voltage. Building that have been design to accommodate DSR can establish new income streams for building owners whilst allowing National Grid to save carbon by avoiding the use of dedicated standby generators which run on fossil fuel and are half as efficient as large fossil fuel power-stations.
Again, early strategic decisions are required to make this possible and form intervention can allow a building to run without active systems for a given period of time in order to qualify for DSR schemes.
Building form ideally is designed to provide multiple functions and benefits. In the example of the design for the UK Pavilion for the Dubai Expo, the humble lift shaft was transformed into a central feature. The 8 lift shafts, besides vertical transportation, each became:
1. Daylight Providers: Each glass lift shaft created striking high-level focal glows drawing the eye up to the reflective ‘infinity’ ceiling.
2. Structural supports: The shafts supported the roof structure removing the need for additional support allowing for a clean, open space and lightweight, non-structural feature-façade.
3. Free Coolth Provision: The misting at the top of the lift shafts provides free evaporative cooling for visitors ascending to the top level.
4. A Unique Visitor Experience: The misting results in dense water droplet cloud at the top of the lift shaft. The creates a unique experience for visitors as they slowly rise into the cloud.
5. External Dynamism. The organic rise and fall of the brightly clouds in each of the eight lift shafts, resulting from the evaporation and remisting as visitors and dry air entered the lift, gave the whole Great Ocean Hall a life-like dynamism.
6. A Riser: The lifts shaft was also designed to serve a practical function and connect services from top floor to the ground floor as well as housing the façade light projection equipment which helped to create the ocean experience.
UK Pavilion lift-shaft mist experience sequence: