Architect and retrofit specialist Paul Testa
Paul is founding director of HEM Architects and has spent more than a decade specialising in low-energy architecture, Passivhaus design and deep retrofit. He has also put his advice into practice by carrying out an EnerPHit retrofit of his own 1970s semi-detached home, giving him both professional and personal experience of the realities involved. He is also a regular expert speaker at our client’s Homebuilding & Renovating Show.
We’ve recently spoken to Paul about some of the biggest questions and misconceptions he encounters from homeowners.
Why the most sustainable home could be the one you already live in
With so much attention focused on building greener new homes, Paul argues that we’re overlooking Britain’s existing housing stock. Retrofitting an older property can avoid the carbon associated with demolition and new construction while tackling the energy performance of homes that will still be standing for decades to come. His view is that improving the homes we already have needs to become as important as building new ones.
Why homeowners should stop treating every improvement as an investment
Paul challenges the idea that every pound spent on a home must translate into increased property value. Better insulation, ventilation and thermal performance can make a house warmer in winter, cooler in summer and healthier and more comfortable to live in. He believes we should think about our homes as places that support our everyday lives rather than simply financial assets for a future buyer.
The mistake of buying individual energy-saving products without a plan
Rather than starting with new windows, insulation, solar panels or another individual measure, Paul recommends developing a whole-house plan first. This identifies the worst-performing areas, considers repairs that will be needed anyway and prevents homeowners completing work now that may have to be altered or undone later.
Are solar panels and heat pumps becoming the new ‘eco-bling’?
Paul is an advocate of low-carbon technology, but argues that homeowners can become distracted by the visible green technology while overlooking the building itself. Solar panels and heat pumps can play an important role, but addressing the roof, walls, floors, airtightness and ventilation can fundamentally change how much energy a home needs in the first place.
Does a heat pump really require a fully insulated eco-home?
Paul says this remains one of the biggest misconceptions around heat pumps. Almost any property can accommodate one if the system is properly designed and correctly sized, although homeowners need to understand what may be required of their radiators, underfloor heating and pipework before making the switch.
The hidden costs homeowners overlook when budgeting for a heat pump
The heat pump itself isn’t necessarily where all the expense and disruption lies. Because the systems operate at lower flow temperatures than conventional boilers, larger radiators and changes to pipework may be required. Paul can explain what homeowners should investigate before accepting an installation quote.
Should you insulate first or install a heat pump first?
There are two competing approaches: improve the building fabric first to reduce its energy demand, or install low-carbon technology sooner to decarbonise more quickly. Paul can explain the advantages and compromises of both and why the right route depends on whether the homeowner’s priority is comfort, carbon reduction or running costs.
Why a heat pump won’t automatically reduce your energy bills
Heat pumps may achieve efficiencies of 300–400%, but with UK electricity considerably more expensive than gas, efficiency alone doesn’t guarantee lower bills. If running costs are the priority, Paul’s rule of thumb is to reduce a home’s heat demand by around 30% first, unless technologies such as solar panels and battery storage are also being incorporated.
What to do when you don’t like the renovation plans you’ve paid for
Paul frequently meets homeowners who aren’t happy with their architect or designer’s scheme but feel unable to challenge it. He can advise on establishing whether the problem lies with the original brief, the service they’ve commissioned or simply poor communication – and what to do before walking away from plans they’ve already paid for.
Why your architect shouldn’t simply draw what you ask for
Paul believes homeowners should tell their designer what’s wrong with their home rather than prescribing the solution. A dark kitchen, freezing room or awkward family layout might lead to an extension, but a good architect should first understand the problem and explore opportunities the homeowner may not have considered.