The energy use in a building is generally that consumed by its services in heating, cooling, cooking, and in electrical systems. Energy is also consumed by specialist processes, by its users and staff in travel to and from the building, and in the delivery and extraction of material. For clarity it is these energy uses that I would like to discuss in this blog, rather than other energy footprints generated by development, such as energy use in construction or production of materials.
As architects are often the lead consultant in building projects, they have an important role interpreting the client’s brief and working with the client in the development of it. The architect therefore directly influences the amount of energy that will be used in the building’s operation once complete. The design that the architect initiates in response to the client’s brief will immediately begin to dictate the terrain and limits within which the consultant team must work. In terms of energy use in operation, it will be the design strategy developed by the services consultant, in collaboration with the architect and client, that has the greatest impact on the new building. Additionally, energy use associated with the operation of the building but external to it, such as users’ journeys to and from the building and deliveries and waste collection, will be a significant part of its overall energy footprint. This aspect is more closely controlled by the client who will already have a site in mind, and in many cases will have delivery and waste strategies already in place. The site strategy that is developed, however, can hugely influence the external energy demand of the new building.
While most briefs are very specific, for example incorporating requirements for occupancy, equipment or processes, it is the architect’s role to propose solutions that represent the most energy efficient route to meeting these requirements; especially as the building’s operational energy use may be high on the client’s agenda for both financial and environmental reasons.
As seen recently in the Stirling Prize winning scheme for Norwich City Council, low-energy domestic buildings can now be affordably produced at scale. The scheme in Norwich, as with others in the country such as Agar Grove in Camden, utilise a design approach called Passivhaus (passive house). Passivhaus originates from the Passivhaus Trust: a not for profit organisation that through testing and research has developed a verifiable system for constructing homes that use almost no energy for heating, while providing high standards of comfort and health. Passive houses typically use 75 percent less energy in heating and cooling than a traditional UK newbuild. Verification is critical to a Passivhaus as it informs the owner and designer of the building’s correct construction and performance in use, and therefore its effectiveness as a low energy home. Passivhaus homes are checked against the original designs and tested once complete. Only through this checking regime can they be finally certified as truly low-energy Passivhaus buildings. Evidence and feedback to date shows that Passivhaus buildings are performing to standard, which is crucial, given that the discrepancy between design aspiration and as-built performance for many new buildings in the UK can be as much as 50-100% [Source: Passivhaus Trust].
Passivhaus can apply to newbuild or retrofitted domestic buildings, however there is currently no equivalent standard for non-domestic buildings. In the UK and around the world, the Building Research Establishment (BRE) assess and certify the design of masterplanning, infrastructure and buildings under BREEAM (BRE Environmental Assessment Method). BREEAM awards a performance rating for projects of between one and six stars. The rating is certified by an ‘impartial assessor’ and takes into account sustainability across a wide variety of categories from energy to transport and waste. A high BREEAM rating requires extensive measures to be taken across key categories, such as reduction of energy use, reduction of consumption of potable water, habitat creation and protection and sustainable management objectives. BREEAM certification is given once the assessor has reviewed the project information to determine compliance with the applied-for standard. Unlike Passivhaus, BREEAM relies primarily on design information and written commitments rather than certification of building materials, construction, performance or post-occupancy evaluation in order to award its certificates. An example of this is that the minimum standards for achieving a BREEAM ‘Very Good’ rating (four out of six stars) do not include any post-occupancy standards. To achieve ‘Excellent’ (five stars) or ‘Outstanding’ (six stars), only one ‘Aftercare’ credit is required, achieved by meeting seasonal commissioning requirements only. BREEAM’s new ‘POS’ or Post Occupancy Stage promotes further post-occupancy assessment but is optional only. For this reason, the gap between design aspiration and as-built performance in UK non-domestic projects remains wide.
Almost as important as controlling the energy use within the building, in terms of its total energy footprint, is reducing the energy required by its occupants, servicers and visitors to reach it. While much of this will depend on the geographical location of the site – such as whether it is in a rural or urban location and which transport links it is close to – once this is set, the architect must work with the conditions determined by the building’s location to control its transportation energy footprint. Examples of the type of measures that can be employed already exist in national and local planning policy, such as minimum numbers of covered bicycle parking spaces, and in larger schemes requirements for provision of new bus stops and EV charging points. While the design of the building cannot prescribe the way that people arrive at it, it can encourage certain travel modes while discouraging others. By way of illustration, a new nursery proposed on the edge of a city centre with good bus, pedestrian and cycle links could significantly reduce energy use and local pollution, while increasing safety by design to exclude car drop-off for everyone except mobility-impaired users. The discouragement in this way of unnecessary motor vehicle use would dramatically reduce the building’s energy footprint and its pollution impact on the local and global environments. Those travelling from further afield to work would also be encouraged to use public transport or other low energy means, in turn reducing energy use in a wider sphere than the building’s immediate community.
So, what, then would a low transport-energy building look like? Subject – as above – to its location, it is certain that measures could be applied within the design of the building and its site to control transport energy usage to a lesser or greater degree. These measures might include:
– Provision of safe, pleasant pedestrian access to the site and building, including links to as many adjacent paths and pedestrian routes as possible, ideally open to the public and including level surfaces enabling full accessibility and provision of lighting between site perimeter and building entrances.
– Provision of public space, if possible, that is dedicated to pedestrians and fully accessible and integrated into the local community.
– Segregated, prioritised cycle pathways integrated into the adjacent cycle or road network, bringing bicycle users safely to storage facilities adjacent to or within the building.
– Provision of covered, preferably indoor, secure bicycle parking for every occupant of the building including future-proof provision for e-bike charging. This should be located as close to the building’s entrances as possible and must be of a type that can be operated without significant physical effort.
– Provision of adequate personal storage and showers within the building for staff/users regularly arriving by bicycle or on foot.
– Depending on the size of the project and space available, the integration of local bus services to bring people into the site and to the doors of the building.
– The minimisation – ideally omission – of private car parking provision, prioritising EVs within any provision. Disabled car parking spaces to be provided and served by EV chargers.
– Provision of EV rapid chargers
– Prohibition of drop-off by private car and prevention of illegal parking within and adjacent to the site to discourage drop-off. This must be coordinated with local parking control in order to prevent overspill parking in nearby streets.
– Management of services and delivery networks to incentivise local pollution-free transportation methods.
In conclusion, control of energy use in buildings ultimately lies with persons or organisations commissioning and operating them. Architects do, however have an integral role in facilitating forward-thinking clients in this field through the design process. They have an equally important role in promoting the benefits of low-energy building delivery to those who may be relatively unaware of its importance. After setting out to achieve a low-energy solution, the most important step a client can take is to ensure that the completed, occupied building meets the original aspiration for performance in use. In order to do this the client must take responsibility for rigorous assessment at all stages of design – particularly when Contractor’s Proposals are presented – to make certain of compliance against the project brief. Accredited schemes with mandatory verification such as Passivhaus are crucial to this process, however without equivalent low or zero-carbon certification for non-domestic buildings, the dream of a low-energy built environment will continue to be elusive.
Photograph: Interactive map of European building energy efficiency by ENERFUND