Glebe Meadow Westleton
Glebe Meadow Westleton

Sustainable fabric + Energy efficiency 

Houses don't need central heating if we build them right. 

 

Amazing but true. With the right thermal efficient fabric and airtightness, the heat from our light fittings, electrical gadgets and body are enough to keep the ambient temperature within a new build at a constant ambient temperature of say 20 degrees. 

 

1) the fabric of the building ie walls, doors, windows, ceilings, roofs need to be as thermally efficient as possible 

 

2) the building then needs to be as airtight as possible so that hot air doesn't escape, and cold air doesn't come in. 

Maximum thermal efficiency + Airtightness = Lower CO2 emissions + Lower running costs =  Sustainable property 

Above - The CIC team onsite at a Beattie Passiv House Build

 

Maximum Thermal Efficiency

Our aim is to build houses that maximise thermal efficiency by choosing highly insulated materials that minimise how much heat is lost through them. 

The U-value measures how much heat is lost through a square metre of floor, wall, window or door. Materials that let out more heat have higher U-values. Houses constructed of bricks or blockwork have a really high U-value and many older properties loose a lot of heat through draughty windows and doors too.

The lower the U-value of the material the more thermally efficient that element of the building fabric is and therefore the lower the running costs. 

 

Passiv Haus - is a standard for energy efficiency in a building that reduces the buildings ecological footprint. It results in ultra-low-energy buildings that require little energy for space heating or cooling.  This is the standard we are aiming for.  Please see Passivhaus Standards for more info on this. 

 

Building regulations require a test on all new builds to establish how airtight the property is. The test involves pressurising a house and measuring how quickly a fan needs to turn to maintain that pressure - the faster the fan, the lower the airtighness. A recently built house might be in the region of 5 - 8 (max 10 for new build regs). Passiv Haus must be below 0.6  

Energy Performance Certificate Ratings - A house with a very poor EPC Rating (eg G) is not energy efficient and will have a higher fabric U-value than another property with a high enery efficiency rating of  A or B. To achieve these levels the property will have to have both a thermally efficient fabric AND be a lot more airtight than conventional, older properties.

 

Emissions from heating existing homes are the single largest contributing factor to the UK's carbon footprint, so all new homes will need to be more sustainable in their design to ensure a higher energy performance. 

 

The Vicarage will be a challenge to upgrade to a more thermally efficient building than it is now as the brick fabric will need to be insulated and the sash windows overhauled to reduce draughts.     

Timber frame construction with concrete floors and closed wall panels. 

 

In the UK we have been using timber frame constructions for hundreds of years and this is the most sustainable product available for new buildings. For every tree that's chopped down to build a house, at least 3 trees are planted. 

 

However, suspended timber floors can be draughty so a concrete floor laid over thick insulation and a damp proof membrane is a better alternative. 

 

The wooden wall panels can either be open - where insulation is fitted on site once the panel is installed -  or closed - where the insulation is factory fitted and the unit comes to site complete. There are pros and cons to both and we will investigate the best alternatives for our site nearer the time. 

 

Cladding - the external layer of the timber panels can be clad in whatever material  is most appropriate for the site and its setting. On the one hand the Vicarage building is red brick, but the grade 2* church alongside the site is stone with a thatched roof. The site is in a conservation area so the material chosen for the cladding - be it brick, natural stone, timber or metal - or whether the external walls are rendered  - will have to blend with the aesthetic of the area. 

 

Roof - as our design is favouring a 1 1/2 storey model, the thermal performance of the entire roof will be a critical factor in the overall efficiency of the building. If we opted for a single storey model (unlikely due to site space constraints) the underside of the roof trusses would be clad with plasterboard and then fibreglass insulation layers would be laid between them.  

 

Windows and doors - ideally triple glazed if budget allows. 

Budget   Building in a highly insulated way with an eye on air tightness is not necessarily more expensive than a conventional build. Timber frame construction also has the added advantage that it is much quicker - a property can be watertight within days and then electricians, plumbers and heating engineers can get to work straight away on the first fix. This type of construction is therefore less weather dependent as we won't have to wait for materials to dry off before the next stage (eg brickwork). In Scotland about 80% of new build houses are contructed with timber frame for this reason.  

Environmental Impact 

Building in a more sustainable way is essential in order to reduce our impact on the environment, especially in terms of minimising global warming and water usage. The energy usage (and bills) are a fraction of what you would expect for a typical house and in this way we believe that we will save residents money and be able to offer a lower service charge than many might expect. Additionally, if budget allows, we would like to add solar PV panels to the rooves to provide free energy to heat water, as well as a grey water scheme and rain water tanks throughout the site to minimise clean water usage. 

Air Quality, Ventilation & Condensation

Within any house moisture will be created through cooking, bathing, breathing, drying clothes etc.  This moist air needs to be ventilated out otherwise condensation may form in areas where there is less air circulation. We will install mechanical ventilation heat recovery system (MVHR) in each property to 

1) extract moist air

2) preheat fresh cold incoming air by means of a heat exchanger

3) provide filtered air within the house, with dust and pollen etc extracted and thus producing a very healthy living environment 

Welcome

Glebe Meadow is a  Community Interest Company established to buy the former Vicarage  in the heart of Westleton and convert it into the social hub for a new development of 20 modern, age appropriate homes for locals aged at least 65.  

 

 

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© Sarah Quinlan