eco upgrade of Victorian terrace to (almost) 2050 standards

Short intro before we start:

This will be a diary of our family's journey from unmodernised & uninspiring,

difficult to heat and hard to treat (solid walls etc) Victorian 2up/2down terrace in Peckham to into warm & cosy contemporary compact eco house.

It will cut 80% of its current carbon emissions by utilising passive haus design principles (with few extras) and will also use natural or recycled materials throughout.

Not only in future use, but also in construction terms we're aiming to make it as green as possible, so the main construction materials used for this part refurbishment, part new built extension, are to be carbon neutral (although we know that the only truly carbon neutral building is the one that doesn't get built).

Below is a sketch summrising the measures taken by us to take it from cold victorian cottage to 21st cebtury healthy eco retrofit. Without going into to much technical detail I rather say that the same simple 3*R rule applies here:

1. REDUCE your building's heat demand - insulate, insulate and make it airtight

2. REUSE renewable and passive energy

3. RECYCLE the heat that is discharged from buildings and waisted

Saving carbon during the build.

Our aim is not only to cut our emissions by 80% during future use of our little house but also to make refurbishment/construction activities as low carbon as possible.

To make the current Victorian house comfortable we decided to build a new 2 storey extension in addition to ecorefurbishment. This according to our structural engineer (and current building regs) required tons of concrete (= approx. 4.5 tonne (!) of cement) for the new foundations and ground floor slab. Our hearths sunk and idea of zero carbon refurbishment went down the drain at the very outset.

Conveniently I knew from working on commercial construction projects that these days cement can be partially replaced with substitutes as fly ash (http://www.sustainableconcrete.org.uk/main.asp?page=41) or GGBS (http://www.sustainableconcrete.org.uk/main.asp?page=42 / http://www.heidelbergcement.com/uk/en/hanson/products/cements/ggbs_and_related_products/ggbs_.htm) which should be so obvious. That's unless you try to buy some on a domestic scale project in London where, as we soon found out, you can only buy a truck loads of ready mix which wouldn't work for our back of the terrace extension.

Few hours of research, and few days later we were finally able to buy 3 tonnes of bagged GGBS directly from Hanson/Heidelberg cement factory (the only GGBS made in the UK) and get it delivered to our house.

In summary:

- 3 tonnes of GGBS replaced 2/3 of cement needed for concrete used for new built part of our project

- We saved approximately 2 tonnes of CO2 (GGBS has only 10% of cement's CO2 emssions of approx 0.81 tonne of CO2 / tonne of cement) + we are using a industrial waste material that would otherwise go to landfill.

- money wise it costed us approximately 10% extra (£50+ a lot of persistence and a good will)

Our other ideas to save carbon/be good to the planet during the first stage of the build included:

- salvaging 1000+ of the original London stock bricks (for local resale via ebay)

- using other bricks and broken down concrete from demolition for a hardcore layer needed below the new slab

- taking all of the scrap metals (copper pipes, steel radiators, lead flashings) to scrap metal yard

..reusing 100+ year old main shell of the Victorian building

To offset the nasty, hard to avoid materials put below the ground we decided to use 13m3 of PEFC certified solid timber prefabricated elements for constructions of both new walls and floors of the new extension.  During it's growth each 1m3 of spruce locks approx 0.25 tonne of CO2 thus easily offsetting the whole project's cement/GGBS CO2 emissions.

For an inner city London project we think that isn't too bad at all...

Low carbon method of construction for the rear extension?

It took us few weeks to make visible progress. In a meantime we removed/salvaged waste from the orginal rear extension, used up all of the carbon saving GGBS in the foundations/ground floor slab and can finally start the interesting part.

Out of many different low carbon construction alternatives to brick and moratar these days our family chosen solid timber prefabricated elements to make the walls and floors of the new extension.

We like timber because it is a natural material that is very suitable for low carbon and airtight buildings, affordable,  easy to work with and will last centuries if kept dry and ventilated. We wanted to have pre-made wall/floor elements delivered to site as this eliminates waste, results in good quality/precision and shortens construction process.  

The downside of this choice is that gluelaminated timber is not something that can be sourced locally in the UK. We had ours travelling from Austria (they also make it in Germany or Scandinavia) but we made sure it was delivered together with other cargo travelling to the UK to minimise transport emissions. 

We are now starting insulating new and old parts of the house, installing triple glazed windows and high performance airtight membranes which should make good subject for the next posts...