Manifesto is a multi-award winning, agile agency of creatives, coaches, strategists and technologists who collaborate with exceptional organisations to help them own their future.

London, United Kingdom
Founded: 2011
Staff: 63
Content Management
User Experience
Digital Design
motion graphics
Video production
Website development
website design
content strategy

and 13 more

Diabetes UK
London Borough of Camden
Cancer Research UK
The English-Speaking Union
Notting Hill Genesis
The Health Foundation
Visit England
Royal Botanic Gardens, Kew
Royal British Legion

and 2 more

Sector Experience
Housing Associations

and 2 more


A sustainable web build for the books

by Gemma Reeve

The Climate Group, an international non-profit organisation, is on a mission to accelerate climate action, to achieve their goal of a world of net zero carbon emissions by 2050, with greater prosperity for all.

The organisation wanted to bring their three websites together under their new brand identity such that it also reflected their strategic direction, and supported their core mission to accelerate climate change.

Our mission is to drive climate action, fast. So it was really important for us that sustainability was at the heart of our recent website overhaul project.

“We were delighted with how Manifesto guided us through the process to create a stand out site presence, that not only showcases our global brand, but does it in a way that is good for the planet.Nazneen Nawaz, Head of Media and Corporate Communications at the Climate Group

Leading by example

Their RE100 website had the largest carbon footprint, accounting for nearly three quarters of total emissions. Whilst the Climate Group website accounted for the majority of the rest. The non-profit wanted to transform the sites into a single site, to allow the cross pollination of content across its initiatives, with the exception of RE100 which was treated as a multisite.

With its overall mission centred around reducing emissions, the Climate Group led by example in every sense. It wanted a site with the lightest code possible. And it wanted its editorial team to understand the logic behind the build, so they could feel empowered to tweak things in line with this logic.

Defining sustainable best practices

There’s very little in the form of data-led evidence to follow when it comes to sustainable web builds. This meant our team had to map out every best practice – and then question each one of them.

Drupal was the best-suited, most up-to-date CMS for the project. To build a sustainable website on this CMS, our team chose the bare-bones theme ‘stable9’. With minimal mark-up and few Cascading Style Sheet (CSS) classes, it ensured all code would directly aid the site’s core functionality. Our additional, self-built custom theme filled in the gaps where stable9 didn’t offer enough flexibility.

We didn't stop there. We tightened up unnecessarily long visitor journeys. We introduced limits, file-type requirements (such as SVG) and optimisation rules around images and icons, which are huge contributors to a site’s heaviness. We also got rid of auto-playing videos, replacing them with static images, and prevented YouTube scripts from auto-loading. This meant energy was only used if a visitor clicked on a video. We stripped down third-party plug-ins, font files and the theme. And on an aesthetics front, we dimmed down the website’s overall colour scheme.

This isn’t everything, but it gives you a good idea of how granular we went to reduce emissions. You can read more on what we did, featured in The Drum here.

Cutting page weights by 50%

This build approach resulted in page weights being reduced by 50% which, in turn, halved the average page load time, increasing the website’s overall SEO and security rankings. The project also saw bounce rates decrease, just as support has increased – two of the charity’s non-environmental priorities.

Since go-live, visitors have spent 40% more time on the website during each session, instead of generating lots of shorter visits. Visitors are also returning more frequently – up from 16% to 22% – which suggests site navigation is clearer and more practical than previously.


Sustainable Design
Sustainable Development Goals
website build
Drupal 9


The Climate Group