Breathing easily

Many buildings currently consume unnecessarily high energy levels ventilating and cooling inhabited spaces, whilst simultaneously producing uncomfortable and unhealthy environments for their inhabitants. Clearly an important factor in energy efficiency is ensuring that buildings are as airtight as possible (current revisions to Part L of the Scottish Building Standards now ensures that air-tightness testing is compulsory) which in turn also increases our attention towards ventilation and cooling. The ‘Build Tight – Ventilate Right’ mantra is becoming evermore vocal, however important lessons must be absorbed from the over-use of mechanical systems and as a consequence of which has seen rising levels of sick building syndromes created by unhealthy indoor environments.

Current issues with MV/NV

The current incentives to avoid mechanical ventilation (MV) and air-conditioning are obvious – both consume high levels of energy, with ventilation alone consuming 5-15% of a buildings running costs. If badly maintained, both systems can also be a source of pollution. That is not to say that natural ventilation (NV) provides an all encompassing solution – poorly designed systems can be very difficult to control, also leading to the introduction of pollution and can be a waste of heat energy. With neither method providing an energy-efficient, clean, controllable and easy to maintain system, a mixed mode or hybrid is becoming the more favoured alternative.

Design Solutions

Passive Stack Ventilation
This approach uses a combination of cross-ventilation, buoyancy and suction enhanced by chimneys or outflows into zones of negative pressure to provide the most effective system of natural ventilation. Cool air is introduced into rooms via opening windows or inlets at low level, and is then heated by solar gains (or other internal heating systems in winter) and gradually rises where the warmed air is extracted through stack chimneys where multiple openings at roof level automatically close on windward and open on leeward sides. Careful consideration must be given to the amount of solar gains provided by glazing, with effective solar shading installed to give sufficient control, and window openings should be designed to ensure that over-ventilation is not an issue. Atria can also perform a similar function to chimneys when using a cross ventilation strategy. Mechanical ventilation does have a part to play when improved air flow requirements are necessary.

Night Cooling
Night cooling is a process which involves harnessing the lower night time external temperature to reduce the temperature of the building fabric, therefore reducing the internal temperature for the following day. Attention however must be given to security and window orientation which can aid lowering the ambient temperature and delay the use of energy consuming cooling equipment.

Culvert systems
Culvert systems exploit the constant temperature of the ground to facilitate buildings with warmer or cooler air which in conjunction with proper controls, solar gains and cross ventilation can also provide internal spaces with a regulated desired temperature. The average temperature of the earth at a depth of 2 metres below ground level is 10°C throughout the year. Air flowing into the ground via a wind tower and distributed to the building via an underground system where the warmed/cooled air can then be introduced and employed to warm or cool rooms. This system can also function in combination with heat recovery.

Conclusions

Reliance neither fully on MV or NV, but the introduction of natural means where possible and restrict where possible the use of mechanical equipment to the role of supporting flow and maintaining comfort levels. Any mechanical ventilation should incorporate lower vent rates and lower specific fan power (i.e. energy required to move a certain quantity of air) to ensure high energy efficiency.

Passive systems of cooling should take precedent over mechanical cooling, again with any mechanical cooling acting as a balancer – any heat should be recoverable too.

Hit the Hütte

Well if you’re going to start somewhere, might as well start big. This is based on an article I recently spotted in the May 2010 (English edition) issue of Detail Magazine – Green Issue. Many hill walkers will be familiar with the concept of bothies or Biwakschachtel to our German friends. Essentially a basic shelter providing hill walkers or farm workers with free basic accommodation in remote areas, several are scattered around the Scottish Highlands and within secluded areas of the Alps. Within the Swiss Alps, 3000m above sea level and 8km as the crow flies from the nearest road fit for traffic, lies the newly constructed Monte Rosa Hütte. Locations for construction do not really get much more isolated than this however you would struggle to find a better example of what architecture can achieve without compromise.

Brief + Design

Swiss Architects Bearth + Deplazes certainly had a task on their hands taking on this brief. Working on an initial design by architecture students from various colleges as part of a four term 'Studio Monte Rosa Hütte' the site provided a number of challenges; no electricity, running water or sewage to tie into and no infrastructure ensuring that transport logistics would be a key issue. The end result is a boulder shaped 3-storey structure that looks as if it has been deposited at random by a slow moving glacier, and further shaped by the extreme weather conditions. The autonomous design allows the building to perform the dual task of blending in with its picturesque surrounding landscape whilst acting as a landmark and orientation point for visitors to the area. This orientation point is continued inside with an internal winding staircase hugging the inside face of the external wall, accompanied with a strip of glazing allow the occupants to constantly consider their relationship with their surroundings. The 6.5million Franc Hütte provides temporary accommodation to over 120 visitors per year, and is only staffed in its most prolific season - between March and September.

Construction + Services

Built in short time windows in spring and summer, construction consisted of a timber prefab frame with a highly insulation facade supported on a star-shaped steel assembly platform. Due to logistical problems, all parts had to be transported on site via 3000 helicopter flights and erected by a team of 35 committed craftsmen living for 5 days at a time in the old Monte Rosa Hütte - weather obviously affecting the program.

Electricity is provided by shimmering 84m² photovoltaic panels placed on the south-facing elevation. Electricity generated is then stored in batteries (200kWh) for use with cooking (with a gas back-up), lighting and running various equipment.

Solar collectors (I had to double check the difference between solar panels and solar collectors – panels are for generating electricity, collectors for generating heat) placed as a band around the base of the structure have the added bonus of reflection from the surrounding snow. This energy is then used to heat water and warm air. In combination with this, the glazing accompanying the internal sweeping staircase has been designed to follow the line of the sun thus maximising the passive radiant heat which is then distributed around the building by minimal ventilation plant. The warm air created is delivered to individual rooms via floor level slits in the doors, and extracted directly above the door (reducing ceiling thickness and minimising lengths of ducts). CFD (computational fluid dynamics) simulation showed that circulation bypass would not be a problem. Extracted air is then channelled to a heat recovery system, and reused to heat water for the four hot showers in the guest quarters. Back-up energy is provided by a combined heat and power system which burns on rapeseed.

Melt water is collected in a cave 40 metres above the hut with a storage capacity of 200m³, thus creating enough water pressure - no pressure booster required. Water is then used for cooking, washing, cleaning and personal hygiene. Microfilter treats sewage, producing „grey water“ which is then reused for flushing toilets or for washing and released into environment in a purified state.

Green Credentials

With most of its energy coming from renewable sources, the building is 90% self-sufficient in water and energy terms (or 60-70% with cooking) ensuring only 10% of the huts energy is flow in by helicopter, which obviously makes a large dent in the carbon footprint. All components and equipment must be market-tested, robust and reliable, as maintenance would be an issue, minimum valve and pumps - less to replace.

A model predicted control system was created to increase efficiency further – an energy management plan monitored that is controlled remotely, in this case the system in controlled in a small office in a far-off town in Switzerland. Due to the fluctuation in the buildings occupancy levels, an intelligent energy management, rather than a system only being aware of the present situation of the building was required. Here is my understanding of how this works: First the scenario – A busy weekend where the hut is at full occupancy, all guests leaving on a Sunday evening and the building is left with a full septic tank and half empty batteries. The weather during the following week is terrible to start with, but improving later in the week. Using a normal control system, treatment of sewage tank would begin, emptying the remaining batteries which in turn signal the backup power to kick in. Using a predictive regulation system (which includes weather forecasting and predicted visitor numbers) knowing that few people will visit during the week and of improving weather later in the week, delays sewage treatment, allowing the batteries to charge fully and empty the septic tank without using heat and power plant backup therefore doing without the use of a back-up generator and saving energy.

Obviously the requirement for constructing any structure in such an isolated location is questionable, particularly when it involves 3000 helicopter flights (almost half of the total kg Co2 for the building over a 50 year period, however total for new building is only a third of the existing hut). However what cannot be overstated is the declaration that this building makes. 70% (two thirds of that being renewable energy) of the huts accumulated energy use goes towards running it, with 30% (just over half renewable) towards construction and eventual demolition over a 50 year period. By good design and overcoming such obvious unyielding issues it provides us with irrefutable evidence that we must challenge the way in which we view solutions to problems, and indeed how we takes these challenges for granted, not seeing them as the opportunities they are. Opportunities which allow us make better use of our surrounding environment and how we can make better use of the waste energy that we produce.

Prologue... Introducing

With the imperative to drastically reduce carbon emissions and with the UK facing a social housing shortage, the construction industry has been presented with an opportunity to alter the way that housing is delivered in the UK. Rather than building with an emphasis only on housing density and share-holder return, concepts such as 'Place-Making' are gaining more weight. It is more important than ever for the construction industry to engage with the communities to increase awareness and ease integration of sustainable technologies allowing a transition to communities independent of fossil fuels.

As an Architectural Technologist, with over 7 years experience in the construction industry throughout the UK and in Germany, I have gained a strong insight into a range of developments as well as building up technical knowledge. Energy performance and sustainable construction/design was a thread I attempted to follow throughout my bachelors, resulting in my dissertation topic on the introduction of Swedish Building Standards in Scotland. This was unfortunately, a thread that I struggled to take into my professional life, both through a lack of experience and technical knowledge, without the full confidence required to argue the case for incorporating sustainable technologies and technique with clients. Having found myself on the sharp end of the most biting recession supposedly since the great depression, I intend on using this experience as an opportunity to focus my energies towards sustainability within the construction industry, and to increase my knowledge of not only greener building technologies, but also how we can design communities holistically, addressing environmental concerns whilst acknowledging time and cost restraints. Having recently been accepted to study Sustainable Community Design at Heriot Watt University in Edinburgh, it is my hope that I will no longer have to wait for another economic bubble to appear before I am able to combine my existing skills and knowledge with this new specialism and start to work on a number of exciting sustainable projects.

.... and so to the purpose of this blog.

It is my intention to highlight existing and new technologies, design methods and case studies that demonstrate that the international building industry is not only capable of meeting the challenges of the future, but is already, and has already provided prospective clients with several examples of how this can be done. This blog will hopefully provide clear and easily comprehensible descriptions that can be understood by individuals not normally associated with the construction industry, or perhaps as they are better known, clients. After all, one of the main obstacles to a sustainable future is the inability to sufficiently communicate with clients and the public in general about the benefits to be had. And somewhere along the way, I will also hopefully be improving my essay writing skills which should come in handy for the masters. Incidentally, this is the first year that Sustainable Community Design has been offered at Heriot Watt University so this blog may hopefully provide an insight into the course for any prospective students or indeed employers.