The paper presents far-infrared (FIR) photometry of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT at 150 μm and 205 μm. Five of these galaxies are detected in both wavebands, and the data are used to model the dust emission at λ ≥ 40 μm, combining two modified Planck functions with T~40–55 K (warm dust) and T~20–23 K (cool dust). The cool dust can contribute up to 60% of the total FIR emission, heated by both the general interstellar radiation field and the starburst itself. The cool dust mass is up to ~150 times larger than the warm dust mass, bringing the gas-to-dust ratios of the starbursts close to Milky Way values. The ratio between the total dust FIR emission in the range 1–1000 μm and the IRAS FIR emission in the range 40–120 μm is ~1.75, with small variations among galaxies. This ratio is about 40% larger than previously inferred from mm-wavelength data. The study also investigates the balance between the UV-to-near-IR stellar energy absorbed by the dust and the FIR energy emitted by the dust, finding that the predicted FIR emission from dust reddening is within a factor of ~2 of the observed value in individual galaxies and within 20% when averaged over a large sample. If the local starbursts are representative of high-redshift (z≥1) UV-bright, star-forming galaxies, their FIR emission will be generally undetected in sub-mm surveys unless their bolometric luminosity is comparable to or larger than that of ultraluminous FIR galaxies, or their FIR SED contains a cool dust component.The paper presents far-infrared (FIR) photometry of eight low-redshift starburst galaxies obtained with the Infrared Space Observatory (ISO) ISOPHOT at 150 μm and 205 μm. Five of these galaxies are detected in both wavebands, and the data are used to model the dust emission at λ ≥ 40 μm, combining two modified Planck functions with T~40–55 K (warm dust) and T~20–23 K (cool dust). The cool dust can contribute up to 60% of the total FIR emission, heated by both the general interstellar radiation field and the starburst itself. The cool dust mass is up to ~150 times larger than the warm dust mass, bringing the gas-to-dust ratios of the starbursts close to Milky Way values. The ratio between the total dust FIR emission in the range 1–1000 μm and the IRAS FIR emission in the range 40–120 μm is ~1.75, with small variations among galaxies. This ratio is about 40% larger than previously inferred from mm-wavelength data. The study also investigates the balance between the UV-to-near-IR stellar energy absorbed by the dust and the FIR energy emitted by the dust, finding that the predicted FIR emission from dust reddening is within a factor of ~2 of the observed value in individual galaxies and within 20% when averaged over a large sample. If the local starbursts are representative of high-redshift (z≥1) UV-bright, star-forming galaxies, their FIR emission will be generally undetected in sub-mm surveys unless their bolometric luminosity is comparable to or larger than that of ultraluminous FIR galaxies, or their FIR SED contains a cool dust component.