Two extensions housing a gym, pool and office feature full height smart glazing in Haslemere, Surrey A CGI image of the contemporary bookend extensions designed for a country house in Haslemere, Surrey featuring smart glass Bookend extensions to a country house in the SDNP feature smart glazing helping to control light pollution and preserve Dark Night Skies

SDNP's Dark Night Skies policy requires innovative design

Posted on October 18, 2018

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In 2016, the South Downs National Park (SDNP) became an International Dark Sky Reserve, bringing with it new planning policies to protect the dark skies above the park. For any design benefitting from large-scale glazing, these policies present a new challenge to overcome.

ArchitectureLIVE was confronted with this challenge when briefed to extensively remodel, refurbish and extend a country house located high on the hills near Haslemere, overlooking the South Downs National Park. Given the location and optimum southerly orientation of the site, our design sought to fully embrace this spectacular location. This was further supported by Best Practice use of natural daylight in domestic buildings to reduce energy consumption during the day (Building Regulations 2010 L1A Conservation of Fuel and Power).

Our design included the extensive remodelling of all existing living accommodation with a new dining, kitchen and library area as open-plan, terminating in a new generous south-facing terrace with optimum views and two two-storey book-end extensions, framing the existing 1920s family home. The new extensions provide an indoor swimming pool and gym on one side and an office and guest suite on the other.

This case study was one of the first projects to be granted planning permission following the Dark Sky designation and demonstrates how technological advances enable greater responsibility and preservation.

Dark Night Skies

The use of artificial light has increased so significantly over recent decades that our view of the universe has been severely impaired. Light pollution not only prevents us from seeing the marvel of the night sky, but also has considerable adverse affects on the natural environment, harming wildlife and damaging human health, not to mention the enormous amount of energy consumed and the detrimental affect this has on climate change. 

Founded by astronomers in 1988, the International Dark Sky Association (IDA), is an American non-profit organisation which seeks to research and educate about the preservation of the night sky as well as promote responsible outdoor lighting. The IDA is now a recognised authority worldwide for the protection of the night sky and its Dark Sky Places programme, which began in 2001, has since certified over 65 Dark Sky Places covering more than 58,000km2 worldwide, awarding five different types of designations. 

Here in the UK, the South Downs National Park (SDNP) became an ‘International Dark Sky Reserve’ in May 2016, the 2nd in the UK after the Exmoor National Park. Other areas in the UK to be awarded a variety of Dark Sky designations include the Brecon Beacons, Northumberland, Galloway Forest Park and Snowdonia. To achieve this accreditation from the IDA, the SDNPA passed a stringent application process demonstrating that there was great support from parish, town and county councils across the area as well as the general public.

The South Downs National Park Authority has since used its role as a planning authority to protect the dark skies above the park, integrating policies into the Local Plan, for designers and users alike to adhere to.

As light pollution is caused by the use of any artificial light at night, new developments within the SDNP now have to take on board the preservation of dark skies, avoiding or, at the very least, mitigating the adverse impact of artificial light appropriate to the location of the development within the SDNP. This leaves a vast array of organisations as well as individuals responsible for a huge range of light sources. 

Finding a Solution…

As stakeholders of our built environment, this places new and - in some areas - conflicting responsibilities on the designers. Whilst energy saving concepts encourage the use of large glazing elements in order to capture solar gain, daylight and ventilation, the Dark Night Sky policies seek to minimise any new glazing that could result in light pollution at night.

Nevertheless, in light of the Dark Night Skies policies, any amount of larger glazing is now considered as follows: 

“… the spill of lights from large open glass windows and sky lights often present a greater source of light pollution than externally mounted lights. Consequently, it is important to control the lighting coming from these types of developments. The design of buildings should reduce the impact of light spill from internal lighting or suitable mitigation measures should be put in place.” (SDNPA Local Plan: 5.64 - South Downs Lightscape Management Policy)

Following a pre-application consultation, ArchitectureLIVE carried out extensive research and collaborated with the SDNPA in order to find a solution to this new challenge. Neither we nor our client wanted to compromise the design which maximises views, natural light and passive solar gain for all new and reconfigured spaces. On the other hand, the use of curtains or blinds at night time is not considered an acceptable solution by SDNPA as their use would be entirely reliant on the end user. We therefore considered the properties of glass - the building material that due to its inherent nature also holds the key for light management. 

Glass Technology

Over the last decades, technological advances have created the opportunity to control light transmission through glass and its inherent, transparent quality. The manufacturing process of glazing allows for the integration of foils and PV cells. These are regularly used for solar protection and building integrated photovoltaics - BIPV, to successfully pin point the right level of daylight whilst either absorbing any surplus energy or using it to be converted into electricity. However, most foils and BIPV cannot accommodate an astronomic cycle or varying states of transparency throughout the day as they have just one fixed state. The exception to this is electrochromic glass.

Electrochromic glass features thinly coated layers of a film made of different metal-oxides. In their natural state, these metal oxides are opaque, however, if electrically charged with a small current the metal ions migrate making the film transparent. The level of transparency can be further controlled incrementally, therefore, also equally control the amounts of artificial light emitted from the building.  

Electrochromic glass or smart glazing is now widely available under a number of trade names and most commonly used to control solar gain and privacy in commercial buildings. 

For our design, the smart glazing is programmed to be switched on to deliver maximum light transmission during the day and switched off at night, therefore, in its non-see-through state, eliminating any new artificial light pollution. The smart glass controllers will be activated by light sensors and set to astronomical time, thereby forgoing the reliance on the end user.

Together with upgraded existing external and internal light sources, surpassing current energy efficiency standards, the SDNP Planning Authority supported our design and the use of smart glass to manage the new, extensively glazed areas, delivering an uncompromisingly contemporary design going hand-in-hand with the preservation of the Dark Night Skies. 

As designers we often find ourselves at the forefront of making policies a reality. The concept of the preservation of the Dark Night Skies, like any other environmental protection, is vital for our wellbeing and the future of our planet. Nevertheless this can only be successfully implemented if the application does not constrain progress. So it seems necessary that every new policy is paired with technological advances to sustain a progressive society.


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