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Heygate Estate Regeneration / London, UK

 

Heygate Estate Regeneration / London, UK

Year: 2013
Use: Housing
Location: London. United Kingdom
Cross Floor Area: 17,640m
Height: 212 stories (38m)

 

The Heygate estate was designed as a low income social housing located at the South London borough of Southwark. It housed over 1200 families for more than three decade. Prior to the 1930s the area consisted of a suburb of victorian tenements which were considerably damaged during the German bombings in World War II. The council there upon decided to demolish and rebuild in the area rather than repair the extensive damages, leading to a major post war regeneration project designed by architect Tim Tinkers which started in the 1960s and was completed in 1974. Due to economic crisis during its construction it had been constructed quickly with limited funds. In the context of the city in the 1970’s the estate had been designed in a manner that separated it from the dirty and polluted surroundings and created a safe and green haven inside. But the rise in unemployment in 1980’s there was in increase in crimes and other anti-social activities and there were social and other issues that arose in the estate from this.

Southern facade required extensive environmental research for developing design strategies. This is due to the duration of direct solar incidence upon this facade which vary from 8-12 hours. The orientation makes its necessary to design a facade which utilise the large solar gains successfully during the cool period and negates scenarios of overheating during the warm period. The design strategy at every step has been tested on the Ecotect and TAS for the best combination of daylight.

Stage1 – The window sizes for units have been derived from the glazing to floor ratios deemed suitable from the Energy index calculation and these are positioned in the facade keeping views and interior spatial quality in context.

Stage2 – There were shading diagrams calculated from Ecotect and strategies has been developed such that each aperture was shaded from direct solar incidence during the warm period when the sun was at the pear azimuth position. This could be achieved by tilting the facade by an angle of 15degree toward the South along with having a horizontal shading device. The applied also served the purpose of creating a private terrance space which added to the living quality of the flat. The tilt was integrated inward into the structure instead of an extension keeping in context the complication of adding cantilevered extensions to the existing structure as well the thermal problems of cold bridge this would lead to.

Stage3 – The facade was finally modified by redistributing window sizes and placing windows vertical to further improve daylight performance in living space.

The average annual wind velocity on the north side is 1.15m/s, addition of projected masses shows a reduction of this wind speed to 0.23m/s. But to create more space for outdoor activities these projected masses have been reduced in number and interspersed with lighter structure which functioned in the same manner as wind breaks. The principle that has been used in deciding the position of these projected masses is that if the height of the mass is ‘H’ then the distance between two masses is ‘20H’.

Site simulations conducted on Winair showed that the wind condition on the south of the building was not as poor as the north; this was due to the protection provided by the existing trees on the site. However the wind velocity of 1.15~2.0m/s in the south can be further optimised as according to the Beaufort scale the most pleasant wind for outdoors is less than 1.5m/s. Also according to spot measurments, the actual maximum wind velocity on south side was 4.5~5.0m/s. To attain this condition there can be additional trees planted to function as windbreaks. However the outdoor spaces on the north which have more drastic wind conditions can not be controlled by plantation as the space on the north is insufficient from adequate trees. Thus temporary light structures that create doldrums like spaces within them can act as windbreaks on the northern side.

The strategy on the south is to increase the number of trees which show a reduction of the average annual wind velocity from 1.15m/s to 0.46m/s. In the outdoor spaces on the north side the addition of projected mass and lighter structures function as windbreaks and reduce the wind velocity in the wind channel from 1.15m/s to 0.23m/s. These conditions are satisfactory for optimal outdoor comfort.

The landscape of the site has been planned integrating the surroundings of the site. The outdoors have been planned around three focal nodes, two to the northern side (Node 1 & 2) and one to the southern side. Node 1 is an conjunction of all pedestrian paths connecting the site to the Elephant & castle and Node 2 is where all traffic flowing in from the rest of the master plan reaches the site, both of these nodes are aimed towards use by the public. Node 3 is planned as a more private buffer zone, which can be used by resident, and people from the residential neighborhood to the south. The outdoor has been zoned (Fig 16) guided by the strategic placements of the public and private nodes. The spaces to the north of the building have been designed as commercial spaces for use by the public who visits the site, whereas the region on the south is a quitter and more private space for the residents of the building as well as for access to the residential floors.The trees existing on the site comprise of only deciduous trees, 15 trees to the northern side and 13 trees on the south. These deciduous trees act as good windbreaks in the warm period but in the cool period they have no foliage and hence their impact as windbreaks reduces. The addition of evergreen trees and low shrubs can make these windbreaks effective even in the cool period and create comfortable outdoor spaces. Outdoor design and Facade has been treated at the same time. The facade design was intended to attract the flow from outdoor into the inside. To do this motive of design, at first solar ray has been tested regarding the incidence angle to secure view to outside. All the circulation from ground level can be reached to the void space through the sloping passage securing accessibility for disabled people. Environmentally, the balcony was projected depending on how much it could provide shading areas.

도심재생 프로젝트의 일례로 런던 엘리펀트캐슬(Elephant Castle) 지역의 Heygate Estate 재생(Regeneration) 프로젝트를 소개한다. 그전에 개괄적 인트로임을 밝힌다. 영국 런던 남부의 엘리펀트캐슬 카운실(Council)과 에스테이트(Estate)간 줄 다리기로 수년간 방치되어 슬럼화된 아파트먼트 지역이다. 2차 대전 종전후 도시 정비가 미숙한 시점에서 들어선 길이 180m의 거대한 볼륨. 당시 신공법이었던 프리캐스트 커튼월의 기본 골격이 견고했다. 에스테이트 내에서 슬럼화가 가장 농후한 지역을 선정해 지속가능성을 타진했었다. 기존 배치와 골조를 재사용하는 리퍼비쉬먼트(Refurbishment)의 일환으로 주된 전략은 다음과 같다.

1. 체감 온도가 중요한 지면(Ground level)에서 빌딩 사이에 형성된 도심지 계곡(Urban Canyon)에서의 바람 유입 조절 -> 건물 표피 온도의 최적화 -> 냉난방 부하 개선

2. 건물 중층에 보이드 형성 -> 열악한 북측 일조 해결 (현대 건축에서 대부분의 키친 및 다용도실은 북측에 면한다) -> 실내 열적(Thermal) 환경 개선

3. 각 세대를 상호 중복형으로 겹배치 -> 실내 열적 덩어리(Thermal mass)의 구속(Trapping) -> 최적의 열적 효율 증명 -> 유지비 개선

이 모두가 낙후된 건물의 재생을 위한 설계적 조치들로 건강한 환경 조건을 만들고, 유지비를 줄여 현실적으로 지속가능성을 담보하는 검증된 해법들이다. 혹자는 도시가 살아야 건물이 산다고 하나 실상은 반대다. 사람이 건강해야 집이 건강해지듯, 건물이 건강해야 도시가 건강해진다.

얼마전 Y대에서 연구용역중인 친환경 건축 규제에 관한 정보를 접했다. 요점은 퍼실러티(Facility)에 의지해 이상적인 공조 환경을 구축하겠다는 것인데, 이에 따른 건축 설비 및 환경 수치 기준 제정에 년간 수백억이 들어야 할것으로 보인다.

하지만 국제 지속가능 건축 포럼 PLEA(www.plea2016.org)에서 쏟아지는 수백편의 논문들에서 퍼실러티로 지속가능한 건축을 실현했다는 사례는 찾을 수 없다. 런던 시청과 서울 시청을 비교해보자. 지속가능 건축은 디자인 프로세스 초기에 반영되어야 한다. 형상 작업(Forming), 재배치(Re-arrangement) 등 초기 과정에서 최적의 터치를 통해 공간을 자생시키는 것이 목적이다. 개축도 물론 포함된다. 옷으로 치면 개인의 체질과 체형에 맞게 옷의 재질을 선정하고 디자인하는 것. 덥다고 옷에 선풍기를 다는 것이 아니다.

지속가능성이란 기존의 것들을 재취합, 재배치하여 새로운 가능성을 얻는 시도다. 채를 통해 불순물을 걸러내는 것. 일종의 오버홀(overhaul) 개념이다. 단순히 퍼실러티로 쉽게 얻을 수 있는 가치가 아니다. 예를 들어, 평균 기온 33도. 평균 습도 80%에 육박하는 여름의 서울 도심지 환경에서 퍼실러티 증설로 증가한 냉방부하는 열원으로 남아 결국 빌딩 숲에 갖히게 된다. 그 열이 다시 실내로 유입된다. 당연히 냉방비는 상승한다. 이런 상황에서 퍼실러티 증설을 독려하는 건축 환경 규제가 해법이 될 수 있을까?

차선책으로서 결국 한국과 같이 연교차가 큰 난해한 기후대의 도심지에서 가장 효과적인 어반 쿨링(Urban Cooling) 방법은 건물 중층의 보이드 형성, 저층부의 비워냄 및 녹지 증설 뿐이다. 보이드로 인한 연면적 축소는 설계적으로 해결할 수 있다. 실제 한국의 필로티 구조는 건강한 미시기후(Microclimate) 형성에 도움이 되는 사례로 종종 소개된다.

서울의 도심환경에서 건축적 지속가능성을 실현한다면, 어디에서든 통용될 수 있을 것이다. 지속가능건축의 상품화도 가능할 것이다. 기존의 법규에 건축 형태의 포밍과 배치에 관한 가이드라인만 추가해도 유럽이 꿈꾸는 이론상 존재하는 지속가능한 어반(Sustainable Urban)도 실현될 수 있을 것이다.

 

Source: https://www.sskas.com

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