Hitting the Wall (Insulation)!

It’s been an intense few months for everyone in the UK (and now globally too…), and a lot has changed for me personally too. I’ve made a decision about “LittleEcoTerrace”, and I’m going to do my best to “finish the job” and see if we can make Superhome status. We already moved the house from a D to an A (CO2 via EPC) for ~10% of its value, but I know there are lots of things we can still do that might just be enough to push our CO2 saving to the 60 % required to get Superhome status.

A bit over a month ago, I passed my final exam (viva) on to become a Dr. of Chemistry, for which I focused on atmospheric chemistry motivated by Climate Change and Air-quality. A personal hero of mine is an American lady called Katherine Heyhoe (and she even liked one my of tweets once… *swoon*), who recently publicised a study showing climate scientists’ credibility is affected by their actions (insideclimatenews article). I strongly believe this, but I think it is more poignant that if even those who can start to understand the sheer scale of impacts climate is having don’t act… then who does?

There are some obvious things that we should be doing for our LittleEcoTerrace project, but we won’t as they should have been done earlier in the project if they were going to be done at all. One of these is extending our insulated floor through our 70s kitchen/bathroom extension, another is installing full mechanical heat recovery (MHR). There are some little ideas that might happen in the future too, like putting a light well in at the top of the stairs… But below are my loose plans for work on the house over the next bit. I am very open to any  suggestions or comments!

Phase 5 – Doing the bathroom

This is the most simple and standard bit of work I want to do. Our bathroom needs some love and most people end up doing this at some point. In our place it has been workable, but not great, since we moved in. We spruced it up a bit with some paint and added the active ventilation (see “Its draught to let hot air escape“). However the whole extension remains hard to heat due to large heats sinks of the floor and ceiling (which I want to tackle in Phase 7). As well as generic aesthetics, I will insulate the (metal) bath.

bathroom on arrival… a few things have changed, but not much…

Currently the bath touches two external walls and un-insulated tile floor. It keeps its heat for a mere few minutes. So i intend to move it slightly away from the walls and put some insulation in the gap and around the bath. I want to replace the metal legs with plastic ones to insulate from the floor too. It’s been an aim ever since we arrived to one day have a proper hot bath!

Phase 6 – Insulating the two internal walls

Two of the large heat sinks are the two solid external walls of the old terrace. The simple and cheapest option would be to do external insulation, but we are rather fond of the traditional Victorian brickwork. Therefore we are looking at internal insulation, and one that doesn’t take that much space from the room. The one that we are often recommended is called SpaceTherm. It is a aerogel, like the insulation used by NASA on the Space Station, it is high performing and takes up little space but is quite expensive.


Phase 7 – Insulating the extension

The extension is a massive heat sink in the winter and overheats in the summer. It is very common and most extensions and badly thought out conservatories you see around will suffer from this. To sort this I’m looking into insulating the walls and ceiling. The floor also needs doing (currently just tile on scree), but I can’t do this without ripping out the kitchen that was put in only shortly before we arrived.

The simplest option would have been to put insulation atop of the flat roof, but as we have solar panels there (see blog post “To PV or not to PV“) it would be troublesome. I’m still looking into this and open to ideas. However, currently the winning idea is to attach kingspan inside to the ceiling of the extension. To make this happen I will have to be convinced that we won’t end up with/can avoid condensation.

I also am keen to have a go at doing external insulation, but as we already have the cavity wall insulated this would have less impact. making sure the (flat) roof covers the extra depth of wall might also pose some challenges.

The story before?

Just for completeness and to put the new work in context… here is a brief history of the work we’ve done so far ( inc. previous renovation and “eco-renovation” ). To summarise the changes to the original house to date i’ve clumped together the broad “phases”. Technically some of these overlap, or the timings are mixed between phases, but for the sake of this blog article I will pretend that I had more of plan…

Phase 0 – From the beginning… 

Many years after the original (~1899-1902) construction of the 2-up-2-down terrace, a 70s extension with was added to the back. This had no insulation. The house also went through a typical modernisation with electricity and central heating.

Phase 1 – Recent updates to house (up to ~5 years before we moved in)

A bit had been done to the house in recent years. Double glazed  windows ( not very good PVC )… and I am disappointed by this, especially as the house had a beautiful wooden and stained glass door about ~1 year prior to moving in… However costs limit the ability to replace these and this highlights the need to do things right first time with the large expenses. A new (modern, but non-condensing) boiler was fitted, which unfortunately died within 5 years. And a recently installed IKEA Kitchen. This is the point it was at when we moved in.

Phase 2 – Floor 

We dug up the whole downstairs floor to deal with a damp problem and added lots of insulation and a new solid wood floor at the same time. (described on blog post “Floored by insulation”).

Phase 3 – Ventilation/Insulation boost

The house was very leaky and poorly insulated. We boosted the insulation in the walls, roof, ceiling hatches, and installed bathroom active extractor at the same time as insulating up all vents (as described in blog post: “Its Draught to let Hot Air“)

Phase 4 – Added solar panels (PV)

We are very fond of these. They produce ~3.3MWh a year (record so far: 3.53 MWh), which approximately equals the gas from our 1st year in the house and the electricity from the year before we moved in (total: ~3.3 MWh). Nowadays we consume a very variable amount of electricity and gas,  depending many people are in house/usage/etc but generally it is a lot lower as we are using energy off the panels. (described on blog post: “To PV or not to PV“)

Solar panels on the main roof

Phase 5 – Yard (Not yet complete!)

An underplayed part of sustainability is lifestyle change. It’s not that sexy, unlike fancy tech solutions but it can make a very large difference to a carbon footprint. We are most of the way through redoing the back yard to make it easy to be a base for cycling. So far this has been re-making the shed into a seat, building a bike shelter, and finally we aim to lay the Victorian quarry tiles we took up from inside the house (upcycle!).


I am not sure whether we will be able to make it to the 60 % Co2 saving requisite for being a Superhome with these savings. My approach to everything so far has been piecemeal and been a big learning journey. I am very keen to reduce the footprint and learn how to do a few things along the way. Whatever happens LittleEcoTerrace is definitely, in a plodding way,  moving towards being an “Aspiring Superhome”.



It’s Draught to Let Hot Air Escape!

Our House was Full of Holes!

The house had rather better ventilation that we would have liked when we got it… due to a hole in the roof! So that was obviously first priority. Seriously though – just walking round the house and holding a ear or a hand to gaps you can hear where you heat is escaping. We obvisouly need airflow to be able to breath and avoid damp buildup, but in reality the old terraces are extremely leaky and that air is carrying money spent on heating a house with it.

The double glazing and uPVC doors were installed a couple of years before we moved in, which is a major and costly part of most retrofits. Although aesthetically these don’t appeal to everyone (myself included), their thermal and draft performance really do beat the wooden doors typical of a house of this age.

The real decisions we had to make were on how to avoid losing precious indoor heat from the house. The power of controlling the flow air and exchange with the outside is huge. If our project were larger we would have probably invested in mechanical circulation combined with a heat exchanger (like these people did); this kind of system give you all the benefits of a leaky house in terms of fresh air and humidity but without the extremely costly heat loss. However, we choose the simplest and easier options to keep the project on budget.

Wall/Loft Insulation

The easiest and cheapest stage in any retrofit project is loft insulation. It has short payback periods, you can buy it cheaply from any hardware company and at the time of writing you can get free loft insulation installed if your house doesn’t met the standard (links at end of article). For us the loft insulation needed topping up by ourselves at small expense as it hadn’t been done properly and we didn’t quality for any grants.

If you have cavity walls, again currently the easiest route is a single phone call to get cavity wall insulation of the government’s energy company obligation ECO schemeThere used to be some scepticism about this as with all “green” technology, but for typical houses the consensus is clear that this is the cheapest and best option. We had the extension done and this took a few hours with little effort under the ECO.

If you have solid walls (like us for the main building) then the question is rather different. Solid wall insulation is costly, but considering the massive amount of house stock for which this is currently the best option it is being funded on and off by the government by schemes including GDHIF (here is a worked example with the grant). It is worth checking if any funding is available whilst if you are thinking about doing any work and I would recommend YouGen as the place to start checking. Solid wall insulation for the two external walls of the house would have been a great option, however we missed the funding window during our works and at the time it was unfortunately out of budget.

Gaps – Ceilings, Loft holes

Whilst re-laying the loft inulsation we released the extent to which the loft hatches were just vents for hot air. There were simply un-insulated boards with gaps, this would have had a massive effect on heat loss. Our approach was to re-board the ceiling to create a new loft hatch, fill up the previous one and insulate both.

Other places you could hear air escaping were by pipes passing through walls where a gap was presen the material would make a gap when expanding or contracting with temperature. These kind of air leaks were solved simply using silicone sealant or expanding foam.

Insulated pipe, but gap for air loss
Insulated pipe, but gap for air loss

Air Vents

We had 3 vent covers downstairs, which when removed really showed the horror of hole size in the walls of the house (photos below). The amount of air that would escape through these would be huge. The controlled/”active” air flow was argued to be the best intermediary, compared against managed/mechanical ventilation by those we spoke to and it makes a lot of sense. Although humidistated fans were mooted as a first option, conversation with people who had installed them lead us to the conclusion that a switch linked to the shower was best. So we installed a single iris fan for the extension to control the humidity. During the summer the windows are often open so it is of little relevance, but it is important to increase ventilation in the winter.

The vents look the same now, they are just filled with insulation and aren’t costing us money.

The bathroom is vastly nicer now with the new fan (photo below), and very much less damp. As the decision was mad to have a single fan, the timer is currently set for 30 minutes and it can also be turned on whilst using the kitchen.

Our house has become less cat friendly. However, by insulating the cat-flap and vestigial vents with kingspan it is obviously noticeable the difference in the drafts.

Of our two fireplaces, one is sealed and the other remains an open flue. We’ve bought a chimney balloon too, and this is only used in the winter to cut out heat losses.

Did it Take Lots of Effort?

These are small changes. They cost very little and make a large difference. The external wall insulation would have been the largest expense if we had done it, but it would have been done by contractors so it wouldn’t have been much effort on our part. Still, the most effort was in installing the loft insulation and insulating the vents which took at most a few hours.

If is possible to achieve a lot more than we have here, and there are lots of great examples on the low energy building database (LEBd). Many people have achieved houses that through design or retrofit do not require heating

The key thing is to remember to still keep the place airy and keep a note on how humid the it is and whether any damp problems exists or are developing, if they are then further air circulation is need. We track this using an arduinio linked to our energy monitor. We’ve not had any issues, but if we do I will install a second fan that would be constantly on and have heat recovery.


– The Green Deal Home Improvement Fund (GDHIF) – grants that can pay upto 67% for energy-saving home improvements

– Passive House Trust (PHT) – the UK national body, which has lots of information and links up

– low energy building database (LEBd) – a database of case studies with more information.

– Cheap heat exchanging extractor fans (<£300 installed and <£5 a year to run)

more links on the blog’s links page