SuperHome Database

Hereford, Portfield Street, Grove Cottage

House Summary

Andy Simmonds and Lorna Pearcey

House Type:
Victorian 4 bed terrace (135m2 )

Carbon saving:

  • Street Infrared_Hereford_PortfieldSt

Measures installed:

  • Condensing boiler
  • Draught-proofing
  • External Wall Insulation
  • Floor Insulation
  • Loft Insulation
  • Low Energy Lighting
  • Mechanical Ventilation Heat Recovery
  • Triple Glazing

Upcoming events

This home is not open for events, for further information about the eco refurb please contact the home owners using the form below.

Personal story:

I am an architectural designer and partner in Simmonds.Mills Architects as well as part-time Chief Executive of AECB – the association for environment conscious building ( I initiated the AECB CarbonLite & CarbonLite Retrofit programmes and led the AECB team supporting the energy aspects of the Technology Strategy Board’s ‘Retrofit for the Future’ competition. I was also instrumental, with others, in setting up the UK’s Passivhaus Trust as an evolution of the CarbonLite programme.


Our motivations for the refurbishment of the house were a combination of environmental, financial and social factors. We wanted to be as sustainable as possible (and reduce our overheads). It’s entirely consistent with Simmonds.Mills values and practices over the last 25 years and in line with AECB activities – how could I not?! I would like to see equitable policies being developed and implemented to support  similar levels of refurbishment being possible for all – a theme underpinning my input into the recent AECB report – ‘Less is More – Energy Security After Oil’.

As for financial reasons, we were thinking of our 20 year plan when we bought the house – we knew we were going to be here a long time. We knew that we needed to extend the house when we moved in anyway due to having twins, so we wanted to improve the energy efficiency at the same time.

When we bought the house it was uncomfortable and very expensive to keep warm. It was much too hot when the heating was on in winter and much too cold when the heating was off. The heating controls were not good. It was physically uncomfortable when we were sat in the cold house and the musty air meant that we were also concerned over air quality (mould spores and ‘soil gases’ were entering the house via the suspended floor above the damp basement. We were worried about the new-borns being too cold and thinking ahead to our old age.

Also see:
Property background:

The Victorian terrace was draughty but stuffy when the radiators were on. It was leaky (literally – rain) and noisy. The nearby trains could be heard throughout the house.

Key changes made:

The main changes we made during the refurbishment, inspired by passivhaus design, included insulating external walls, the loft and the floors as well as installing triple glazing throughout the house. The house is now 100% draught free with low space heating demand – fresh filtered air comes into the rooms via the MVHR system. Of course we can and do open the windows when we want.

Measures installed in detail:

  • Gas condensing A rated non system boiler, plus energy efficient external pump, weather compensated controls, all hot and cold water pipes highly insulated, extra insulation applied to hot water cylinder (HWC)
  • Floor insulation: Sheeps wool under floor U=.13/.17
  • Loft insulation: 400mm thick mineral fibre U=.09
  • 100% compact fluorescent lights
  • Heat Recovery System: MVHR  certified 90%
  • Ventilation: Careful detail and site supervision. Air test results = 0.97/m3/h/m2 @50Pa
  • Triple glazing: low E glass/Argon filled. 250mm EPS external U 0.115
  • 3 no. triple glazed Fakro roof lights
  • Low space heat demand.

For more on this project, please see CarbonLite Standards on Eco-Renovation  and and the AECB Database

Benefits of work carried out:

With the extension we have doubled the size of the house but we use 80% less gas and 45% less electricity than the average house – can also afford 21 – 22 degrees C throughout the heating season, though we keep our bedrooms a little cooler at around 20C. I have a garden office – unfortunately using electric heaters and am planning to sub meter this! Actual consumption figures can be seen on the AECB low energy buildings database.

We particularly like the air quality, warmth and comfort levels now in the house – the good air quality a direct result of the Mechanical Ventilation and Heat Recovery system (MVHR). You can also really feel the benefit of the rigorous Passivhaus ‘100% draught-proofed’ approach, this is important for comfort, but also to ensure that the MVHR is as efficient as it can be in terms of electricity consumption. I am also very happy with the temperature ‘gradient’ across the property – this means we can have warmer rooms and cooler rooms (the living rooms and bathrooms are warmer than the bedrooms) – overall we have far fewer radiators than before, though we kept the old larger radiators as more surface area means we can have lower temperature water from the boiler which is more fuel efficient than hot water for space heating.

We also like the fact that the triple glazing and insulation has cut out a lot of external street (and train!)  noise and the house now feels very calm & peaceful. In really hot weather we can either leave the MVHR on (summer bypass mode – which means there is no heat recovery going on – just air coming in at the external temperature i.e. cooler at night) or we can keep windows open at night to cool the house with cool night air. Opening the windows at night has more cooling effect, but sometimes we choose to leave the windows closed and juts rely on the MVHR because of street noise or insects – what would be an improvement here is to incorporate an insect mesh into the windows.

An added benefit of undertaking this retrofit has been that it has made all of us very conscious of energy efficiency generally in our home. It has made the children think about the energy we use in a different way (it becomes a precious thing that we are taking care to use sparingly – whilst getting a great result from using much less – they get the ‘more with less’ concept!)  I have learned so much as a result of this one – comprehensive – project and I feel empowered by the result.

Favourite feature:

All of them – the fact that they are integrated gives me the most satisfaction. If pushed I would say the airtightness/insulation combo is the most satisfying as we hold onto the energy in the home. It feels frugal harvesting ‘free energy’ that we can actually retain in the house – when the sun is shining in, the oven is on, we leave the bathwater cooling, or we have guests…

Business name:

Simmonds.Mills Architects

Business overview:

Simmonds.Mills Architects design low-energy domestic and non-domestic projects to the AECB Silver, Passivhaus and EnerPHit energy standards.

SuperHomer Andrew Simmonds is a Partner in Simmonds.Mills Architects and part-time Chief  Executive of AECB, The Sustainable Building Association. His architectural and building experience includes historic buildings, innovative and traditional materials and the development of energy efficiency products for the mass market.

Andrew led the development of the AECB energy standards and initiated the AECB CarbonLite programme. He also led the AECB team supporting the Technology Strategy Board’s Retrofit for the Future competition, including developing the low energy buildings database, and was closely involved in setting up the Passivhaus Trust to bring the work of AECB CarbonLite into the mainstream.

For more information, visit

Common questions and answers for this SuperHome

What contractor and system did you use for the external wall insulation?+

We used an accredited Permarock installer. Recently we have used Joyners who were good. The external wall insulation system we used is Permarock Platinum (250mm neopor type EPS).

Contact this homeowner

Assessment types

SuperHomes Assessed

A home that has been visited and assessed by us and confirmed as reaching the SuperHome standard, which demonstrates a 60% carbon saving.

Homeowner Reported

Information has been provided by the homeowner about their home and energy use prior to the installation of measures and following their installation which demonstrates a carbon saving. This information has not been verified.

Remote Assessed

The homeowner has provided information on their home including what measures have been installed which has enables an assessor working on our behalf to assess their carbon savings. This home has not been visited to verify the measures installed.


This home has not been assessed, but the homeowner has reported what measures have been installed. It may be that this home is awaiting assessment.