Off-site Construction – GHA Knowledge Base

Summary

A demonstration project of two ‘flat pack’ homes built using a standardised platform kit-of-parts, delivered to site without the need for a heavy goods vehicle and assembled by a semi-skilled and diverse contractor team.

The 3-bedroom homes have been designed and built to achieve Passivhaus standards (uncertified), to be maintenance-free externally for thirty years, have low running costs and be available for social affordable rent.

The project was one of several small-scale projects commissioned by the London Borough of Ealing who were seeking to explore a range of MMC solutions.

Key information

Client: Ealing Council
Developer: Buildeco Offsite Architecture
Sub-contractor: B-Line
Architects: C.F.Moller Architects UK
Location: Northolt, Ealing
Engineers/consultants: Conisbee Consulting Engineers, XCO2 Energy, Butler & Young Associates (M&E)
Panel Manufacturer: GMOC
Project type: New-build
Number of homes: 2
Sector: Social Housing
Key dates: Handover – 16th November 2020

Key facts/highlights

Whole life carbon calculation of the building taken from the extraction of raw materials through to manufacturing, transport, assembly, operational use, end of life and disassembly
At the end of the buildings life, the system is reconfigurable to form other types of buildings
Fabric first approach with Passivhaus principles (not certified)
Reduced foundation costs, due to lighter building weight
Building assembled within ± 1mm
Site assembly by hand by a diverse, trained, multitask workforce
Delivered entirely in ‘white vans’, removing use for an articulated lorry
Achieved EPC ‘B’ without renewables, with renewables has the potential to achieve EPC ‘A’

Energy performance

Energy Use Intensity (EUI): 53 kWh/m²/yr
EPC rating: B
Space heating demand: 22.7 kWh/m²/yr
Dwelling Fabric Energy Efficiency (DFEE): 42.3 kWh/m²/yr
U values:
- Roof – 0.14 W/m²K
- Ground floor – 0.13 W/m²K
- Suspended floor – 0.16 W/m²K
- Walls – 0.14-0.15 W/m²K
- Door – 0.45 W/m²K
- Windows vary between 0.8-1.6 W/m²K, g-value 0.52-0.64
The tenant reported that to date their monthly bill in the coldest winter month was just £23
MVHR installed

Whole life carbon/resource efficiency

The buildings can be disassembled at end of life, with panels being able to be reused and reconfigured. It is designed in such a way it can be disassembled in reverse order
Use of MMC to minimise material waste
Carbon reductions of between 30-50% were achieved due to the lightweight structure requiring shallower foundations and fewer site deliveries
Only 2 skips were used for waste material throughout project delivery

Materials and construction

The UK manufactured panels of the build system are constructed from non-combustible materials, Light Gauge Steel (LGS) & Magnesium Oxide boards (MgO boards), and the assembly of the panels is within ± 1mm and the overhaul dimensions of the building when assembled is within ± 2mm in all directions.

Floor, walls, ceiling and roof panels are almost identical
The building components do not use any nuts, bolts or screws and the whole building is assembled using one tool
To assemble the full superstructure from ground level to roof took a total of 28 man-days in three phases

EV charging

There is provision for a 32amp single phase charging point.

Thermal comfort and resilience

CIBSE TM52 compliance
Energy-efficient lighting
Solar control glazing

Access to green space and amenities

120/150m² private rear gardens
250m to the local bus stop
Shops within walking distance

Safety and security

The scheme complies with Secured by Design.

Scalability/buildability

The system is a standardised and is scalable using Panelised MMC category 2 (Pre-Manufacturing – 2D primary structural systems), which can then be designed to any size.

Quotes

David Baptiste, Head of Housing Development, Ealing Council

“The project was completed to a high quality build and energy standard which is endorsed both by the development department and residents living in the accommodation.”

Robert Turner, Project Officer, Ealing Council

“The Quality of the finished produce was excellent – better than the other demonstration projects, it achieved the promised thermal performance, the buildings are contemporary and attractive, and they are constructed from materials and using techniques that will minimise long term maintenance.”

Further information and images

https://www.build-eco.com/sectors/current-project/

Case study kindly funded by MCS Charitable Foundation

Summary

Kiss House are developing a multi-storey single dwelling Passivhaus construction system, allowing the rapid on-site assembly of high specification homes using low-complexity, repeatable and clean methods.

The system is intended to be scalable and initially, a series of front runner projects will be constructed to prove the concept.

The Kiss House team were experts in best practice low energy construction. Their background was in bespoke one-off housing. Whilst bespoke house builds can lead the way in terms of innovation, they are generally highly inefficient as they require a project team to reinvent the wheel every time. They are like prototyping exercises, never really to be repeated. Kiss House wanted to find a vehicle to transfer all the lessons they’d learned.

Key information

Client: Various
Developer: Kiss House
Architect/Designer: Kiss House
Location: Multiple
Engineers/consultants: Kiss House
Project Type: New build
Number of homes: 1-10
Sector: Private Housing
Key dates: Handover – Start date late 2021

Key facts/highlights

Kiss House have created a building system that can:

Achieve Passivhaus certification
Be low in embodied energy
Work across different geographical locations.
Be configured into different housing typologies
Easy to erect
Use natural materials
component-based design for manufacture and assembly (DfMA) flexibly off-site
Be predominantly timber and using waste and native timber
Displace petrochemical-based products eg steel and concrete
Eliminate wet trades
Significantly reduce local distruption/traffic movements
Be measurable and adaptable
Enable a feedback loop for continual improvement and innovation
High embodied carbon materials are also excluded by design

Energy performance

Kiss House is using wall and floor sensors to monitor fabric performance and room sensors to monitor internal conditions. They will be collecting energy usage data to compare with predicted data. They are developing their own soft landings equivalent for this with a BPE partner.

Energy Use Intensity (EUI): Building EUI inclusive of building-mounted renewables as required to achieve Passivhaus Plus certification is anticipated to be < 10kWh/m²/yr
EPC rating target: A
Environmental Impact Rating target: A
Space heating demand: As this project is being designed to meet Passivhaus Plus in a variety of locations and orientations, it should be capable of delivering lower space heating demand than 15 kWh/m2/yr
Heat pump:5 kW PUHZ_H_Monobloc ASHP with a SCoP of 3.18 for DHW & 4.01 for space heating
Dwelling Fabric Energy Efficiency target (DFEE): 32 kWh/m²K
Dwelling Emission Rate target (DER): -5.79 kgCO2/m²/yr (Net Zero Carbon)
U values: Area weighted U-value of opaque elements targeting 0.11 W/m²K
Air tightness: High performance triple glazing with Air tightness < 0.6 ACH @ 50 Pa (equivalent to ≈0.7 m³/h/m² @ 50 Pa)
PV will be sized to achieve Passivhaus Plus so will vary with location

Whole life carbon/resource efficiency

Kiss House uses product design industry CAD modelling technologies to develop the construction system in high granular detail that is constructed using off-site manufacture as a system of non-volumetric building materials. This reduces waste and allows high-density transportation.

Material and process embodied carbon information is embedded in the building model, giving full transparency of carbon values for all components used in the construction system and allowing targeted component development to reduce environmental impact. High embodied carbon materials are also excluded by design.

Stages A1 to A3 ( from BS EN 15978) Embodied carbon data are embedded into product data to enable fast analysis of component level carbon.

Thermal comfort and resilience

Passivhaus PHPP frequency of overheating checks
CIBSE TM59 design methodology for the avoidance of overheating in homes

Healthy and non toxic materials

Kiss House is pursuing WELL certification.

International WELL Building Institute announced plans to enter the single-family home market in May this year. They have created a panel of experts to collaborate on establishing the standard and Kiss House anticipates adopting the standard as soon as it becomes available.

Scalability/buildability

The construction system allows a majority of building assembly to occur off-site
Highly detailed models enable precise purchasing of materials, reducing waste
The construction system is process specific and site activities are defined as part of the system
On-site activities are repeatable and building-agnostic (i.e. the processes on site are the same whatever the building format or size).
One guiding principle is to always exceed minimal space requirements
Adaptability is inherent in the system due to non-load-bearing walls and easily accessible services

Quotes

Mike Jacob, Director of Product and Innovation, Kiss House

“We realised that to develop new product innovations we would have to engage in radical collaboration as a team; with academia and research institutions and with specialist skills and expertise within the wider industry.
It has been a steep learning curve for the last three years, we have evolved hugely as we’ve begun to understand and harness the power of product innovation and to decarbonise construction in our attempt to respond to the need for better housing.
Ultimately, we realised that the only way to achieve our goals and help change housing was to develop a new building.”

Further information and images

https://www.kisshouse.co.uk/

Case study kindly funded by MCS Charitable Foundation