Contractor

Name : Sandwood Construction Ltd.

Contact : Richard Garland

Construction Manager

Name : Bere Architects

Contact : Justin Bere (Justin.Bere@bere.co.uk)

Stakeholders

Function : Certification company

MEAD: ENERGY &ARCHITECTURAL DESIGN
Kym Mead (kym@meadconsulting.co.uk)
Passivhaus Plus Certification

Function : Environmental consultancy

Energelio
clement.castel@energelio.fr
Environmental Engineers that carried out the self-consumption analysis

Contracting method

General Contractor

Owner approach of sustainability

One is a scientist, the other a medic. Both were interested in going somewhat further than the minimum requirements of the building regulations in order to create a prototype all-electric, plus-energy, grid-connected, low carbon building that might show how buildings can provide community infrastructure benefits as well as benefits for the occupants.

Architectural description

Lark Rise is an ultra-low-energy, contemporaryand healthy home. It is a detached two-storey, two-bedroom dwelling of 175m2located on a North West facing slope on the edge of the Chiltern Hills inBuckinghamshire, England. The main entrance is on the upper floor, facingtowards a sheltered entrance forecourt to the South East. The main views are tothe North West from the upper floor reception spaces, and from the bedrooms onthe lower floor. The garden consists of a level lawn, overlooking a smallorchard and rolling farmland that extends as far as the eye can see. The upperfloor contains an entrance area, cloakroom, and open-plan kitchen/living space,and the lower floor contains two bedrooms, two bathrooms, a boot room, and autility room.

The main garden façade faces North Westand is entirely glazed, with large windows and a terrace. Solar gains arelimited because most of the glazing faces to the North West. Partiallyunderground construction to reduce visual impact on a protected landscape areaand northerly orientation certainly help to maintain stable and comfortabletemperatures in Summer and Winter and help avoid summer overheating.

If you had to do it again?

We are doing it again for another client, using low-cost construction on a level site at 1/3rd of the cost.

Building users opinion

Very happy that the house is gaining so much interest around the world as a pioneering example that might one day be the norm.

Energy consumption

• Primary energy need : 80,00 kWhpe/m².year
• Primary energy need for standard building : 200,00 kWhpe/m².year

Calculation method : Other

CEEB : 0.0001

• Final Energy : 42,00 kWhfe/m².year
Breakdown for energy consumption :

Heating: 22%
DHW: 10%
MVHR: 9%
Power sockets: 25%
Cooking: 5%
Miscellaneous: 9%
Lighting: 19%

More information :

Lark Rise consumption was monitored during 2 tenancy periods, user preferences can cause variations in the floating demand seen in the cooking and lighting levels, however, we would expect the miscellaneous circuit to show a relatively constant demand between tenancies because the circuits which are fed by the ‘miscellaneous’ submeter shouldn’t be greatly affected by user preference, however there was an unexpected consumption on the 'miscellaneous' circuit (pumps etc) during the second tenancy period. At present the cause of the variation in miscellaneous power demand is not known. However, the pump within the septic tank burnt out in November 2017, and it is possible that the increased consumption could be due to this.

Envelope performance

• Envelope U-Value : 0,12 W.m^-2.K^-1
More information :

•Below ground walls: concrete basement retaining structure (250mm), exterior Foamed glass insulation (360mm). U-value= 0.118 W/(m2K)
•Above ground walls: Prefabricated timber frame, with mineral wool insulation (300mm), and larch rain screen cladding. U-value = 0.137 W/(m2K)
•Prefabricated Glulam box-beam ceiling, PIR insulation (280mm) and multi-ply hot-melt membrane, extensive green multi-ply bituminous membrane roof. U-value= 0.074 W/(m2K)
•PUR insulation (50mm) and screed with UFH and floor finishes on top of concrete slab (300mm) and foamed glass insulation below-slab (410mm) U-value= 0.076 W/(m2K)
•Passive House certified, insulated triple-glazed timber-framed windows & doors. Ug= 0.60 W/(m2K), Uf= 0.72 W/(m2K), g-value= 62%
•Entrance door: Bayer Passive House insulated timber-framed door. U-value = 0.81 W/(m2K)


• Building Compactness Coefficient : 0,21

Indicator :

• Air Tightness Value : 0,41

Users' control system opinion : It's an incredibly simple and robust building in use. 

Real final energy consumption

42,00

42,00

2 016

Systems

Heating system :
• Heat pump
Hot water system :
• Heat pump
Cooling system :
• No cooling system
Ventilation system :
• Natural ventilation
• Nocturnal Over ventilation
• Double flow heat exchanger
Renewable systems :
• Solar photovoltaic
• Heat pump
• Renewable energy production : 200,00 %

Zehnder, Paul Novus 300
eff. specif. HRE: 91%
Maximum flow rate [m³/h] 300
Electric power input [W] 90
Sound power level [dB(A)] 43
Reference flow rate [m³/h] 210
Reference pressure difference [Pa] 50
SPI [W/(m³/h)] 0,22
heat exchanger

12kWp PV installation on the roof with a 13kWh battery store

Solutions enhancing nature free gains : Since most of the glazing is sub-optimally oriented to face North West, it needed to be made from super-clear glass with a high g-value in order to maximise winter heat gains

Smart Building

BMS :

Very simply that the heat pump will heat the hot water to a few degrees above set temperature if there is excess sun.
The building use, PV production, battery storage and import or export can be seen in real time via the Tesla application on a mobile phone. This information is being used to tune the building and to decide what the next steps might be (e.g demand shifting or change of user habits eg switching off lights and IT and gaming equipment on standby.)

Smartgrid :

not yet applicable, but may follow

Users’ opinion on the Smart Building functions : Interested in viewing the information provided by the Tesla app.

GHG emissions

• GHG in use : 16,00 KgCO₂/m²/year

Methodology used : Indirect emissions from electrical power consumption are estimated in PHPP through the use of electrical emission coefficients in Germany (GEMIS)

Life Cycle Analysis

This is a very interesting topic, but not yet assessed for this building. On another similar project, but with 1/4 the generating capacity, we found that the embodied energy from the building's construction could be paid back in 60 years. This building is

Eco-design material : N/A

Water management

All waste water is processed on site using a low energy septic tank and zero energy natural water polishing system based on natural bacteria in a peat store.

Indoor Air quality

Other similar projects of ours have been independently monitored, tested and assessed with the conclusion that they provide optimal conditions with optimal RH generally around 40% with any peaks being flushed away within an hour by the heat recovery ventilation system. CO2 levels have been found to be optimal, generally between ambient external conditions and an upper level on occasions no greater than 1000ppm. F8 incoming filters have been found to control incoming pollen and particulates. Healthy construction using natural materials has been found in another project to result in a very low VOC count, both from the building construction materials and from household products.

Health & Comfort

Health & comfort : The above indoor air and humidity conditions contribute to very healthy and comfortable conditions. Also both summer and winter temperatures have been found to be very comfortable, with negligible seasonal, daily or hourly fluctuations.

Calculated indoor CO2 concentration : 500-800ppm

Measured indoor CO2 concentration : 500-800ppm

Calculated thermal comfort : 21 degrees centigrade in summer and winter

Measured thermal comfort : approx 21 degrees centigrade in summer and winter

Acoustic comfort : The concrete construction with first floor screed floating on XPS insulation makes for an extremely comfortable acoustic condition.

Product

LIGNO TREND Roof system
Klimaholzhaus
Ralf Harder (R.Harder@lignotrend.de)

Product category : Gros œuvre / Charpente, couverture, étanchéité

Load-bearing insulated CLT ceiling component

Good

Kaufmann Zimmerei und Tischlerei, Reuthe, Austria - first floor timber frame structure and finishes.

Shoeck Isolators for balcony connections

Urban environment

n/a

Building Environmental Quality