LILAC: Low Impact Living Affordable Community

Last modified by the author on 31/01/2014 - 12:30
  • Building Type : Collective housing > 50m
  • Construction Year : 2013
  • Delivery year : 2013
  • Address 1 - street : Lilac Grove, Victoria Park Ave LS5 3AG LEEDS, United Kingdom
  • Climate zone : [Cfc] Marine Cool Winter & summer- Mild with no dry season.

  • Net Floor Area : 1 676 m2
  • Construction/refurbishment cost : 2 221 617 €
  • Number of Dwelling : 20 Dwelling
  • Cost/m2 : 1325.55 €/m2
  • Primary energy need
    62.78 kWhpe/m2.year
    (Calculation method : Primary energy needs )
Energy consumption
Economical buildingBuilding
< 50A
51 à 90B
91 à 150C
151 à 230D
231 à 330E
331 à 450F
> 450G
Energy-intensive building

LILAC is the UK's first affordable, ecological cohousing project. A community of 20 households and common house, the buildings are made with the ModCell prefabricated straw bale construction system, assembled by LILAC members using local straw. The excellent insulation properties of straw, combined with airtight construction, triple glazing, and heat recovery ventilation, reduce energy and CO2 emissions to a minimum. A community owned Solar Hot Water & Photovoltaic scheme reduces energy & CO2 emissions further. The site has a sustainable urban drainage system to minimise water use and run-off, and the landscape includes herb gardens and allotments shared with the wider community.

The LILAC homes have received UK Energy Performance Certification (EPC), according the SAP 2009 assessment procedure.

(Cost data includes the specific construction costs of the homes + fees & site preparation, excluding parking and urban sewerage).


Contracting method

General Contractor

Type of market


Energy consumption

  • 62,78 kWhpe/m2.year
  • 200,00 kWhpe/m2.year
  • Primary energy needs

    Space heating [kWh/m2.a] average = 35.73
    Hot tap water [kWh/m2.a] average = 39.22
    Lighting & appliances [kWh/m2.a] estimated = 30.00

Envelope performance

  • 0,19 W.m-2.K-1
  • The external walls and roof construction is a glulam timber frame, filled with straw bales the internal walls and floors uses a conventional timber frame. The external walls are rendered using lime render and finished with cedar cladding to cover the structural frame elements, floor and roof levels.
    ModCell is a prefabricated system consisting of load bearing, storey-height glulam framed panels. The panels are filled with straw and lime rendered on both sides providing the internal and external finish. The ground floor panels are delivered to site and craned into position. Prefabricated floor cassettes are fixed into position over the ground floor structure, followed by the next storey of panels. The roof structure is also formed using straw filled ModCell panels. Typically, there are 16-18 panels needed to build a three-bedroom house and a two-storey home can be erected in just 2.5 days.
    The ModCell panels are not manufactured in a conventional factory. Instead, a Flying Factory is set up to provide temporary manufacturing facilities near to the construction site. This reduces transport emissions and fits in with the ethos of benefiting local communities. Appropriately, ModCell uses farmers’ barns to produce the panels and the straw is often sourced from the same farm or from nearby, again this reduces transport emissions and keeps the value of the project in the local economy.
    Pre-shaped and drilled glulam sections are delivered to the Flying Factory in Ikea-like, flat pack form ready for assembly into the structural frames. The straw bales are shaved down to size using a bandsaw to provide an even surface ready for rendering. The bales are placed in the frame and built up in layers in a stretcher bond. Wooden dowels are driven in to the bales to ensure they are locked in position to each other and the glulam frame.
    Lime render is applied to both sides of the panel, two build up coats are spray applied and levelled with a day or two between coats. After 10 days the render has cured sufficiently to allow the panels to be transported to site ready for installation. A finish coat of render is applied post installation. Lime render is used because of its breathability allowing moisture to move freely in and out of the wall. LILAC residents got involved in the assembly of the panels in the Flying Factory.
    The uValue of the ModCell walls is 0.19. The roof at LILAC, also made using straw as insulation, and has a uValue of 0.15. This exceeds the current building regulation requirements for walls at 0.35 and roofs at 0.25. The airtightness of the panels is also very good. The combination of high levels of insulation, airtightness and triple glazing used at LILAC results in significantly reduced energy consumption. The scheme as a whole meets CSH Level 4. Preliminary modelling showed that the apartments would have a yearly space heating demand of 22.78 kWh/m2 and the houses 33.23 kWh/m2. Using the ModCell system means that homes are 25% more energy efficient than traditionally constructed homes built to the 2010 Building Regulations Part L. The use of renewable materials like straw and timber, that absorb CO2 out of the atmosphere as they grow, means that there is an average of 12.25 tonnes of CO2 locked up in each house.

    EN 13829 - q50 » (en m3/h.m3)

  • 2,75

More information

Billing data is currently being collected.

Real final energy consumption

    104,95 kWhfe/m2.year


    • Gas boiler
    • Gas boiler
    • Solar Thermal
    • No cooling system
    • Double flow heat exchanger
    • Solar photovoltaic
    • Solar Thermal
  • 30,00 %

Urban environment

    As a co-housing scheme, members share facilities in what is known as a common house, which includes a laundry, communal cooking and eating space, a play area and office space. The common house is a place to meet and socialise as well as where the day to day management of the society is based. Each house and apartment has their own kitchen and bathroom like any other home. This communal approach to sharing, cuts energy use and promotes a sustainable way of life as residents are encouraged to grow food and provide a supportive environment for older and vulnerable members.
    White Design also designed the landscape and the principles of cohousing informs many aspects of the layout of the site. The houses and apartments are arranged around an informal courtyard with a pond at its centre. The pond harvests rainwater as part of the Sustainable Urban Drainage scheme (SUDs). One third of the site is set up as a shared landscape with allotment gardens, which will be used by the residents to grow their own food and reduce their ecological footprint. Car spaces are also limited to reduce the carbon emissions from transport and all residents sign an agreement on joining which commits them to the philosophy of the society.
    LILAC’s community and sustainability agenda, was the reason it chose to build using straw. “We chose straw for its environmental credentials and because it allowed the community to get involved in the construction process,” explains Paul Chatterton, resident and co-founder of LILAC.

  • 5 000,00 m2
  • 16,00 %
  • 1 000,00


    ModCell Traditional Panel


    [email protected]

    Structural work / Passive system

    ModCell® is one of the first products to make large-scale, carbon-negative building a commercial reality.

    The ModCell® system utilises the excellent thermal insulation qualities of straw bale construction to form prefabricated panels, made in a local Flying Factory™.

    ModCell® allows super-insulated, high-performance, low energy ‘passive’ buildings to be built using renewable, locally sourced, carbon sequestering materials that include straw bale and hemp to create a less than zero carbon construction system.

Construction and exploitation costs

  • 4 251 338,00
  • 38 471,00

Indoor Air quality

    Good indoor air quality is achieved through the use of natural, renewable, non-toxic building materials and finishes, including straw, PEFC timber, lime renders, and low-VOC water based paints and varnishes. Whole house ducted heat recovery ventilation brings continuous fresh air into the buildings.

GHG emissions

  • 10,60 KgCO2/m2/year
  • SAP & SBEM UK Energy Certification Methodology [Dwelling Emissions Rate]

  • 80,00 year(s)

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Oliver Style

CEO in Praxis Resilient Buildings

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